(CNN) If President Donald Trump pulls the United States out of the Paris climate agreement, it likely won't be a quick, overnight process. The exit could take as long as one to almost four years.

Trump is expected to withdraw from the Paris Agreement , according to two senior US officials familiar with his plans.

He will announce his decision in the White House Rose Garden at 3 p.m. Thursday, he tweeted . He ended his tweet with: "MAKE AMERICA GREAT AGAIN!"

I will be announcing my decision on Paris Accord, Thursday at 3:00 P.M. The White House Rose Garden. MAKE AMERICA GREAT AGAIN!

When former President Barack Obama formally entered into the Paris Agreement in 2016, he did so as an "executive agreement" in which he didn't need Senate approval. This is why Trump can now leave the Paris Agreement without consulting the Senate.

The precise mechanism for withdrawal hasn't yet been determined, and White House officials cautioned plans could change until Trump makes his decision public. Language for the withdrawal was still being prepared Wednesday, and will likely include specific legal conditions crafted by Trump's administration.

After that, the rules mandate a one-year notice period, which would mean a withdrawal in late 2020 -- after the next presidential election on November 3, 2020.

1. At any time after three years from the date on which this Agreement has entered into force for a Party, that Party may withdraw from this Agreement by giving written notification to the Depositary.

2. Any such withdrawal shall take effect upon expiry of one year from the date of receipt by the Depositary of the notification of withdrawal, or on such later date as may be specified in the notification of withdrawal.

The UNFCCC has nearly universal membership and provides the underlying framework for international cooperation to combat climate change. This led to the Kyoto Protocol and then the 2015 Paris Agreement.

Any country that leaves the UNFCCC "shall be considered as also having withdrawn from this Agreement," according to Article 28 of the Paris Agreement.

The US could leave the UNFCCC with one year's notice , which gets it out of the Paris Agreement without having to wait until November 2020.

Yes, it's possible to remain in the agreement and just fail to meet any of its terms.

Certain parts of the agreement are legally required, but one key factor is that it doesn't bind countries to actually meet their climate targets . For example, there are no sanctions if the United States breaks its promise of reducing greenhouse gas emissions 26% to 28% below 2005 levels by 2025.

But this option may not be the likely route, since two senior officials say Trump is expected to withdraw from the climate deal.

Established at the 2015 conference, the Paris climate agreement between 195 countries pledged to reduce greenhouse gas emissions and avoid the most catastrophic impacts of climate change.

The Paris Agreement was in part brokered by Obama and was seen as a major breakthrough after the previous accord, the Kyoto protocol, failed to include the US and China, the world's two biggest polluters.

Obama touted it as the "best chance we have" to save the planet.

The US committed to reducing carbon emissions by 26-28% in a decade in signing onto the agreement. The main driver of the reduction was Obama's Clean Power Plan, which would have closed coal-fired power plants.

A host of countries -- from China to Germany -- have committed to stay with the Paris Agreement regardless of whether the United States leaves it. </s> President Donald Trump on Thursday will announce his decision on whether to keep the United States in a landmark global pact to fight climate change, after a source close to the matter said he was preparing to pull out of the Paris accord.

Trump said on Twitter on Wednesday night he would make the announcement at 3 p.m. (1900 GMT) on Thursday in the White House Rose Garden, ending his tweet with “MAKE AMERICA GREAT AGAIN!”

An American withdrawal, promised by Trump during the 2016 U.S. presidential campaign, would deepen a rift with U.S. allies and align the United States with Syria and Nicaragua as the world’s only non-participants in the landmark 195-nation accord agreed upon in Paris in 2015.

The White House remained tight-lipped about Trump’s decision. “The president has listened to people from all sides and ultimately he’s going to make the best decision for … the American worker,” White House spokeswoman Sarah Sanders said.

The source, speaking on condition of anonymity, said on Wednesday Trump was favoring an exit and was working out terms of the planned withdrawal with U.S. Environmental Protection Agency Administrator Scott Pruitt, an oil industry ally and climate change doubter. The source said any withdrawal announced by Trump could have conditions or caveats that were under discussion.

The Vatican, which under Pope Francis’ insistence has strongly backed the accord, would see a U.S. exit as disaster and “a huge slap in the face,” Bishop Marcelo Sanchez Sorondo, a senior Vatican official, told the Rome newspaper La Repubblica.

At their meeting last month, the pope gave Trump a signed copy of his 2015 encyclical letter calling for protecting the environment from the effects of climate change and backed scientific evidence that it is caused by human activity.

U.S. supporters of the pact said any pullout by Trump would represent an abdication of American leadership on a leading issue of our time and would show that the United States cannot be trusted to follow through on international commitments.

The pact was the first legally binding global deal to fight climate change. Virtually every nation voluntarily committed to steps aimed at curbing global emissions of “greenhouse” gases. These include carbon dioxide generated from burning of fossil fuels that scientists blame for a warming planet, sea level rise, droughts and more frequent violent storms.

Scientists have said a U.S. withdrawal from the deal could speed up the effects of global climate change, leading to heat waves, floods, droughts and more frequent violent storms.

During the campaign, Trump said the accord would cost the U.S. economy trillions of dollars with no tangible benefit. Trump has expressed doubts about climate change, at times calling it a hoax to weaken U.S. industry.

The Republican vowed at the time to “cancel” the Paris deal within 100 days of becoming president on Jan. 20, part of an effort to bolster U.S. oil and coal industries.

Since taking office, he has come under pressure from some advisers, close U.S. allies, corporate CEOs, Democrats and some fellow Republicans to keep the United States in the accord.

The United States, under former President Barack Obama, had committed to reduce its emissions by 26 percent to 28 percent from 2005 levels by 2025. The United States, exceeded only by China in greenhouse gas emissions, accounts for more than 15 percent of the worldwide total.

Last year was the warmest since records began in the 19th century, as global average temperatures continued a rise dating back decades that leading climate scientists attribute to man-made greenhouse gas emissions that trap heat in the atmosphere.

In Berlin, German Chancellor Angela Merkel, who pressed Trump to stay in the pact last week at a meeting of the G7 industrialized nations, on Thursday described the accord as essential and said she was pleased many other governments agreed.

Merkel met with Chinese Premier Li Keqiang, and they pledged to continue fighting climate change.

China, which overtook the United States as the world’s biggest emitter of greenhouse gases in 2007, and the European Union will seek on Friday to save the Paris agreement, with Li meeting top EU officials in Brussels.

In a statement backed by all 28 EU states, the EU and China were poised to commit to full implementation of the agreement, officials said.

The European Union is not considering imposing trade sanctions on the United States if Trump withdraws, EU Climate and Energy Commissioner Miguel Arias Canete said in Copenhagen.

United Nations Secretary-General Antonio Guterres tweeted on Thursday, “Climate action is not just the right thing to do, it is the smart thing to do.”

In Moscow, Kremlin spokesman Dmitry Peskov said Russia attaches great significance to the accord, and “the effectiveness of this convention is likely to be reduced without its key participants.”

Marshall Islands President Hilda Heine, whose Pacific island nation already is grappling with rising sea levels, expressed disappointment with Trump’s expected move but applauded other countries for redoubling their commitments.

“My country’s survival depends on every country delivering on the promises they made in Paris – our own commitment to it will never waver,” Heine said in a statement. </s> President Donald Trump tweeted Wednesday evening that he will announce his decision on whether the United States should leave the 2016 Paris Accord Thursday at the White House.

Trump will announce his decision on the Paris Agreement in the next few days.

Trump, who has called global warming a “hoax”, promised during his presidential campaign to pull the US out of the deal.

What’s not quite clear yet is whether Trump intends to pull out of the Paris agreement itself, or the entire treaty underlining all global climate change negotiations, called the United Nations Framework Convention on Climate Change.

More on this as it develops.

China says it will work with the European Union to uphold the worldwide agreement on climate change even if the US pulls out.

Last week, more than 20 Republican senators, led by Senate Majority Leader Mitch McConnell, sent a letter to Trump asking him to leave the Paris Climate Agreement.

Hundreds of United States companies, including Nike, Starbucks and Mars, also signed a joint letter warning Mr Trump a withdrawal would threaten “American prosperity”.

She’s criticizing what she says are “destructive and short-sighted” decisions by the Trump administration. The deal relies heavily on reductions in emissions by big polluter nations, and the United States is the world’s second-biggest carbon dioxide emitter behind China. While a shift of focus back onto fossil fuels will undoubtedly provide jobs growth in the short-term, whether the president believes in climate change or not, the future of energy is in renewables.

Some northern European countries are criticizing the USA for its expected withdrawal from the Paris climate accords.

In Denmark, climate minister Lars Christian Lilleholt said that “if true, this is a really, really bad signal from the United States”.

The European Union and China spell out their continued commitment to the deal in a draft joint statement, obtained by CNN, which is slated to be published Friday regardless of what Trump announces.

Musk indicated that he had been trying to persuade Trump to remain part of the climate agreement.

Under Obama, Washington had pledged to reduce greenhouse gas emissions by 26-28 percent below 2005 levels by 2025. The organization’s main Twitter page quoted Secretary-General Antonio Guterres as saying, “Climate change is undeniable”.

A frustrated German Chancellor Angela Merkel later warned that Europe “must take its fate into its own hands”, citing the differences with Washington on climate change as evidence of their divergent paths. Tesla’s Elon Musk threatened to quit White House advisory councils if the president pulls out. His agency was responsible for numerous multilateral issues, including climate change and ozone depletion. The U.S., he said, is “well positioned to compete” with the agreement in place and staying in means “a seat at the negotiating table to ensure a level playing field”.

A spokesman for the American Petroleum Industry, which represents US oil and gas companies, said it had no position on the Paris agreement, but pointed out recent declines in USA carbon emissions to near 30-year lows – a trend driven by increased natural gas use replacing coal. </s> Not long after President Donald Trump announced today that the United States would withdraw from the Paris climate accord, Mayor Jim Kenney announced that Philly will continue to honor the historic agreement to lessen the country’s carbon footprint in an attempt to fight the global effects of climate change. They say that climate changes are natural, and they say that the Paris accord will slow economic growth and cause higher energy costs.

“At what point does America get demeaned?” he continued.

“Industry must now lead and not depend on government”, wrote Jeff Immelt, CEO of General electric, according to Fortune. Resistance to Trump’s move quickly bubbled up in statehouses, city halls, corporate boardrooms and homes across America.

Alden Meyer of the Union of Concerned Scientists called Trump’s move “reprehensible”. Mayors of more than 85 cities across the U.S. signed a letter on Thursday announcing a commitment to reduce emissions and push clean energy.

The National Climate Change Secretariat said on Friday that Singapore will continue contributing to the global effort to address climate change.

President Donald Trump announced his intention for the United States to leave the Paris climate agreement on Thursday in a lengthy and rambling speech that veered into inaccurate territory several times. “We’re going to grow rapidly”, he said.

“The agreement is a massive redistribution of United States’ wealth to other countries”, Trump said. “You won the election with a manufacturing jobs agenda”.

Without mentioning the USA specifically, Li said that “China in recent years has stayed true to its commitment” and pointed out that his was one of the first countries to ratify the 2015 Paris Agreement.

Mr Trump said though that he was open to renegotiating the deal, or creating a new agreement, “on terms that are fair to the United States, its businesses, its workers, its people, its taxpayers”.

In a memo to Apple employees Thursday afternoon, Cook expressed his disappointment with Trump’s decision to pull out of the global agreement. The accord calls for countries to revisit their individual pledges every five years, with the hope that nations will adopt stricter limits as the price of cleaner energy technology drops.

Trump’s claim that the Paris accord would achieve “tiny, tiny” temperature reductions was attributed to MIT.

British Foreign Secretary Boris Johnson said Britain would continue to press the U.S.to reduce unsafe emissions even if Trump pulls out.

China overtook the United States as the world’s biggest emitter of greenhouse gases in 2007 but analysts see the USA withdrawal as an opportunity for China to burnish its image as a global leader. </s> President Trump announced Thursday that the United States will withdraw from the Paris climate accord of 2016, making it the largest and most influential country not to participate in the international agreement aimed at mitigating climate change.

While Trump said his decision was the first step in an effort to see if there was a “better deal” for the United States, the decision to opt out has been met with concern from many in the international community. In New Jersey, reactions have been largely negative.

Here is what some New Jersey lawmakers and advocacy organizations had to say about the decision.

Menendez said the decision “will have grave consequences for generations to come.”

“It signals to the world that in the face of collective challenges, the U.S. will choose a path of isolation rather than engagement, based on a willful denial of fact,” he said in a statement. “By capitulating to the demands of fringe voices who reject science and promote reliance on the dirty energy sources of the past, the United States is abdicating our leadership and our responsibility to be stewards of the environment.”

Before Trump formally announced his intention to withdraw, Booker went on a 12-tweet spree to denounce the impending decision. He also released a statement ahead of the final decision claiming that a withdrawal would be a “historic blunder” for the nation “that would put the interests of a few big polluters and climate deniers before American security, the economy, and the environment.”

“The rest of the world is charging ahead with or without the support of the United States government,” Booker said. “The United States can either lead the world and reap the benefits of new jobs, new innovation, and new opportunities, or the world can leave us behind.”

Norcross said Trump was “prioritizing corporate polluters over the health and well-being of our children and grandchildren.”

“We should be following sound science, embracing global cooperation and building a 21st century clean energy economy,” he said in a statement. “This administration continues to do the opposite, which is preventing our country from moving forward. Building the clean energy economy is the real way we’ll bring high-wage jobs to America.”

MacArthur said climate change is a “critical issue” and that the United States must act as “good stewards” of the environment. He did not outright endorse or reject Trump’s decision to withdraw.

“In any future agreement, we must protect American workers from a competitive disadvantage and ensure that nations across the globe also carry their weight,” he said.

Pallone, the ranking Democrat on the House Energy and Commerce Committee, said Trump’s “shortsighted” and “negligent” decision puts the future at risk.

“By abandoning this agreement, President Trump is showing the world that an American commitment can be reversed on a whim,” Pallone said. “This devastating decision abdicates our role as a global leader, and breaks our promise to nearly nations to work together to address climate change.”

At a Tuesday night town hall meeting, Lance said that he supported the Paris climate agreement but that he wished it imposed stricter regulations on other nations. He has not released an official comment since Trump’s decision to withdraw.

“I hope — but I don’t know the answer to this– that the administration won’t leave the Paris agreement,” Lance told constituents in Cranford on Tuesday. “I would have preferred an agreement that is stronger regarding emissions from other countries — China and India, for example.”

Sires said he was disappointed in Trump’s decision but that he hopes the administration and Congress can “work together” to curb carbon emissions.

“This shortsighted and selfish act not only damages our nation’s credibility abroad, but also endangers the future of our planet for the sake of scoring political points,” Sires said in a statement. “By withdrawing from these commitments, we are telling the international community that the U.S. government is not serious about addressing climate change.”

On Twitter, Pascrell said the decision to pull out of the agreement was “based on propaganda pushed by anti-climate hard liners.”

Payne said that Trump’s decision “sends a signal that the United States will not honor its commitments to our international partners.”

“Climate change increases extreme weather events and natural disasters like Hurricane Sandy, one of the deadliest and costliest storms in U.S. history,” he said.

“President Trump cannot continue to bury his head in the sand about the devastating consequences of climate change at the expense of our planet’s future,” Watson Coleman said in a statement. “This decision is proof that even in his inadequacy as our nation’s leader he has surrounded himself with people who are just as ill-equipped or ill-advised to make decisions with international implications.”

On Twitter, Murphy said New Jersey must push back on Trump at the state level.

“Pres. Trump’s decision to pull out of Paris Accord will do irreparable harm to the world. Future generations will judge us on how we react,” he said on Twitter.

“Pulling out of the Paris Climate Agreement will go down as one of the worst human rights abuses of the 21st century,” Johnson said on Twitter.

Jeff Tittel, director of the New Jersey Sierra Club

“Even though Trump pulled out of Paris this afternoon, we still had two coal plants in New Jersey close today: PSEG’s Hudson and Mercer plants,” he said. “The country will still move forward with clean energy and New Jersey will next year. Our state will see the most consequences from climate change including sea level rise and flooding. This is only the beginning of the battle and we will continue to fight to protect our planet!”

Ed Potosnak, executive director of New Jersey League of Conservation Voters

“By withdrawing from the agreement to reduce the toxic emissions that are causing the Earth to warm, President Trump has made the U.S. an outlier like Syria, the other nation opposed to the Paris accord,” he said. “The president’s colossal mistake makes it more important than ever to ensure that New Jersey has a governor and a Legislature committed to establishing a clean energy future by creating green jobs and transitioning to a clean energy economy.” </s> U.S. President Donald Trump interacts with reporters as he welcomes Vietnam's Prime Minister Nguyen Xuan Phuc in the Oval Office at the White House in Washington, U.S. May 31, 2017. REUTERS/Jonathan Ernst | Jonathan Ernst / Reuters

WASHINGTON — President Donald Trump said Thursday he was withdrawing the U.S. from the Paris climate agreement, striking a major blow to worldwide efforts to combat climate change and distancing the country from many allies abroad. He said the U.S. would try to negotiate re-entry on better terms.

"As of today, the United States will cease all implementation of the nonbinding Paris accord," Trump said during a White House Rose Garden announcement. Suggesting renegotiating re-entry was not a major priority, he said, "If we can, great. If we can't, that's fine."

By abandoning the world's chief effort to slow the tide of planetary warming, Trump was fulfilling a top campaign pledge. But he was also breaking from many of America's staunches allies, who have expressed alarm about the decision.

Under former President Barack Obama, the U.S. had agreed to reduce emissions to 26 per cent to 28 per cent of 2005 levels by 2025 — about 1.6 billion tons.

But Trump said the agreement disadvantaged the U.S. "to the exclusive benefit of other countries," leaving American businesses and taxpayers to absorb the cost.

Scientists say Earth is likely to reach more dangerous levels of warming sooner as a result of the president's decision because America contributes so much to rising temperatures. Calculations suggest withdrawal could result in emissions of up to 3 billion tons of additional carbon dioxide in the air a year — enough to melt ice sheets faster, raise seas higher and trigger more extreme weather.

The U.S. is the world's second-largest emitter of carbon, following only China. Beijing, however, has reaffirmed its commitment to meeting its targets under the Paris accord, recently cancelling construction of about 100 coal-fired power plants and investing billions in massive wind and solar projects.

White House talking points obtained by The Associated Press said the Paris accord was "a BAD deal for Americans" and that the president's action would keep "his campaign promise to put American workers first."

"The Accord," the document went on to say, "was negotiated poorly by the Obama Administration and signed out of desperation."

"The U.S. is already leading the world in energy production and doesn't need a bad deal that will harm American workers," it read.

The White House had signalled earlier in the week that withdrawal was likely, but Trump has been known to change his mind at the last minute on such major decisions.

White House aides were divided on the topic and had been deliberating on "caveats in the language" as late as Wednesday, one official said. </s> Former President Barack Obama said on Thursday that the cities and businesses of the United States should step up to reduce greenhouse gases after President Donald Trump announced that America would withdraw from the Paris climate change accord.

The mayor of Pittsburgh, pushing back on Trump's statement that he was elected to represent the citizens of that former steel-making giant rather than those of Paris, condemned the withdrawal.

Tech entrepreneur Elon Musk immediately announced he will quit presidential advisory councils. Disney CEO Bob Iger said he was out, too. General Electric Chairman and CEO Jeff Immelt said "Climate change is real. Industry must now lead and not depend on government."

"The United States joins Syria, Nicaragua & Russia in deciding not to participate with world's Paris Agreement. It's now up to cities to lead," Pittsburgh Mayor Bill Peduto, a Democrat, said on Twitter.

Trump said at an announcement at the Rose Garden on Thursday that the United States would withdraw from the international agreement negotiated under Obama, citing a desire to protect American jobs and fuel what he has claimed would be three percent economic growth.

Related: What It Means That Trump Is Leaving the Paris Climate Agreement

Because Obama didn't ask the Senate for approval of the Paris accord, Trump can act unilaterally without the consent of Congress. Democrats, however, could slow down any action on the floor in retaliation of the decision and tie any pending nominations to the issue, actions that won't change the outcome but frustrate Republicans and the White House.

Obama said in a statement that a withdrawal means an abdication of American leadership.

"The nations that remain in the Paris Agreement will be the nations that reap the benefits in jobs and industries created. I believe the United States of America should be at the front of the pack," Obama said in the statement.

"But even in the absence of American leadership; even as this Administration joins a small handful of nations that reject the future; I'm confident that our states, cities, and businesses will step up and do even more to lead the way, and help protect for future generations the one planet we've got," Obama said.

Related: California and Other States Step Into the Climate Policy Void

Reaction on Capitol Hill was mostly partisan, with Republicans standing by the president's decision, praising the U.S.'s withdrawal as good for the economy. "President Trump has once again put families and jobs ahead of left-wing ideology and should be commended for his action," Republican Senate Majority Leader Mitch McConnell said.

But some Republicans in Congress opposed Trump's move. Sen. Susan Collins of Maine said on Twitter: "Climate change requires a global approach. I'm disappointed in the President's decision to withdraw from the Paris Agreement."

Republican Rep. Carlos Curbelo of Florida, who is expected to have a tough re-election in his swing district in south Florida, lobbed a series of tweets in opposition.

Trump had pledged on the campaign trail to withdraw from the 2015 Paris climate accord, which is a non-binding agreement that asks that all signing countries — rich and poor — take concrete steps to reduce their carbon emissions in the face of climate change.

The Obama administration pledged a 26 to 28 percent cut in U.S. emissions, which Republicans have criticized for potentially having a negative impact on the American economy and its energy sector.

Former Sectary of State John Kerry said on MSNBC that the move to withdraw from the Paris deal was "an extraordinary abdication of American leadership."

He noted that the program was voluntary, and the United States was not forced to do anything under the accord.

"It was a voluntary program. We designed the program," Kerry said. "The president was not truthful with the American people today, and the president who talked about putting 'America first' has now put America last."

Withdrawing from the climate deal could take three years, European Commission President Jean-Claude Juncker said this week.

And French President Emmanuel Macron, German Chancellor Angela Merkel and Italian Premier Paolo Gentiloni said in a joint statement Thursday that they take note "with regret" the U.S. decision to pull out of the 2015 agreement.

The three leaders say they regard the accord as "a cornerstone in the cooperation between our countries, for effectively and timely tackling climate change."

They added that the course charted by the accord is "irreversible and we firmly believe that the Paris Agreement cannot be renegotiated."

Macron, Merkel and Gentiloni say they remain committed to the deal and will "step up efforts" to support the poorest and most threatened nations.

U.N. spokesman Stephane Dujarric called Trump's decision a "major disappointment for global efforts to reduce greenhouse gas emissions and promote global security."

Canadian Prime Minister Justin Trudeau said on Thursday "We are deeply disappointed that the United States federal government has decided to withdraw from the Paris Agreement" and said Canada is committed to fighting climate change.

Trump on Thursday left open the possibility of renegotiating what he called a better deal that would put American taxpayers first, and suggested the climate deal was a ruse that put the United States at a competitive disadvantage.

"The agreement is a massive redistribution of United States wealth to other countries," Trump said.

Former President Bill Clinton said on Twitter: "Walking away from Paris treaty is a mistake. Climate change is real. We owe our children more. Protecting our future also creates more jobs."

And Goldman Sachs CEO Lloyd Blankfein said in his first tweet from a verified account that "Today's decision is a setback for the environment and for the U.S.'s leadership position in the world," adding the hashtag #ParisAgreement.

The governors of New York, California, and Washington state said in a statement that they would form a "United States Climate Alliance" which they called "a coalition that will convene U.S. states committed to upholding the Paris Climate Agreement and taking aggressive action on climate change."

A speaker at a protest near the White House called the move "treason" and the crowd chanted "lock him up," a play off of Trump supporters' chants targeting Hillary Clinton during the presidential campaign.

Trump's announced withdrawal from the climate deal was not unexpected. On Wednesday in a tweet in which Trump said he would announce his decision on Thursday, the president ended with his signature phrase: "Make America great again." </s> President Donald Trump announced America's shock withdrawal from the Paris climate accord Thursday, prompting a furious global backlash and throwing efforts to slow global warming into serious doubt.

In a sharply nationalistic address from the White House Rose Garden, Trump announced the United States would immediately stop implementing the "bad" 195-nation accord.

"I cannot, in good conscience, support a deal that punishes the United States," he said, decrying the "draconian financial and economic burdens the agreement imposes on our country."

Trump repeatedly painted the pact -- struck by his predecessor Barack Obama -- as a deal that did not "put America first" and was too easy on economic rivals China, India and Europe.

"I was elected to represent the citizens of Pittsburgh, not Paris," he said. "We don't want other leaders and other countries laughing at us anymore. And they won't be."

Trump offered no details about how, or when, a formal withdrawal would happen, and at one point suggested a renegotiation could take place.

"We're getting out but we'll start to negotiate and we will see if we can make a deal that's fair. And if we can, that's great. And if we can't, that's fine," he said.

That idea was unceremoniously slapped down by furious allies in Europe, who joined figures from around the United States and the world in condemning the move.

"The agreement cannot be renegotiated," France, Germany and Italy said in a joint statement.

The United States is the world's second largest emitter of greenhouse gases after China, so Trump's decision could seriously hamper efforts to cut emissions and limit global temperature increases.

Amid Trump's domestic critics was Obama, who said the United States was "joining a handful of nations that reject the future."

Nicaragua and Syria are the only countries not party to the Paris accord, the former seeing it as not ambitious enough and the latter being racked by a brutal civil war.

Hillary Clinton, Trump's opponent in last year's White House race, called the decision to pull out a "historic mistake."

"The world is moving forward together on climate change. Paris withdrawal leaves American workers & families behind," she said in a tweet.

The Democratic governors of New York, California and Washington states formed a quick alliance, vowing to respect the standards agreed on under the Paris deal.

In New York, some major buildings, like the World Trade Center and City Hall, were lit green in solidarity with the climate agreement, echoing a move in Paris.

With much of the implementation of the accord taking place at the local level, the Paris accord's supporters hope the deal will be in hibernation rather than killed off entirely.

Trump's decision is likely to play well with the Republican base, with the more immediate damage on the diplomatic front.

The US president called his counterparts in Britain, Canada, France and Germany to explain his decision.

But traditional US allies were uncharacteristically blunt in their condemnation of the move, which comes amid already strained relationships with the hard-charging president.

Germany said the US was "harming" the entire planet, and European Commission President Jean-Claude Juncker called the decision "seriously wrong."

Ever the showman, the 70-year-old Trump had given his decision a reality TV-style tease, refusing to indicate his preference either way until his announcement.

Opponents of withdrawal -- said to include Trump's daughter Ivanka -- had warned that America's leadership role on the world stage was at stake, along with the environment.

A dozen large companies including oil major BP, agrochemical giant DuPont, Google, Intel and Microsoft, had urged Trump to remain in the deal.

Ultimately, the lobbying by Trump's environmental protection chief Scott Pruitt and chief strategist Steve Bannon urging the president to leave won out.

In the wake of the announcement, Tesla and SpaceX boss Elon Musk and Disney chief Robert Iger announced they would no longer take part in presidential business councils.

"Climate change is real. Leaving Paris is not good for America or the world," Musk said.

GE head Jeff Immelt said he was "disappointed" with the decision: "Climate change is real. Industry must now lead and not depend on government."

White House officials acknowledged that under the deal, formal withdrawal may not take place until after the 2020 election.

Hours ahead of Trump's announcement, China's Premier Li Keqiang pledged to stay the course on implementing the climate accord in a joint press conference with German Chancellor Angela Merkel, and urged other countries to do likewise.

China has been investing billions in clean energy infrastructure, as it battles to clear up the choking pollution enveloping its cities.

China and the US are responsible for some 40 percent of the world's emissions and experts had warned it was vital for both to remain in the Paris agreement if it is to succeed.

The leader of Asia's other behemoth, Indian Prime Minister Narendra Modi -- who is due to visit the White House shortly -- has said failing to act on climate change would be "morally criminal."

Trump's announcement comes less than 18 months after the climate pact was adopted in the French capital, the fruit of a hard-fought agreement between Beijing and Washington under Obama's leadership.

The Paris Agreement commits signatories to efforts to reduce greenhouse gas emissions that cause global warming, which is blamed for melting ice caps and glaciers, rising sea levels and more violent weather events.

They vowed steps to keep the worldwide rise in temperatures "well below" two degrees Celsius (3.6 degrees Fahrenheit) from pre-industrial times and to "pursue efforts" to hold the increase under 1.5 degrees Celsius. </s> WASHINGTON (AP) — President Donald Trump will announce his decision on whether to pull the United States out of the Paris climate accord during a Rose Garden event Thursday afternoon.

Trump promoted his announcement Wednesday night on Twitter, after a day in which U.S. allies around the world sounded alarms about the likely consequences of a U.S. withdrawal. Trump himself kept everyone in suspense, saying he was still listening to “a lot of people both ways.”

The White House signaled that Trump was likely to decide on exiting the global pact — fulfilling one of his principal campaign pledges — though top aides were divided. And the final decision may not be entirely clear-cut: Aides were still deliberating on “caveats in the language,” one official said.

Everyone cautioned that no decision was final until Trump announced it. The president has been known to change his thinking on major decisions and tends to seek counsel from both inside and outside advisers, many with differing agendas, until the last minute.

Abandoning the pact would isolate the U.S. from a raft of international allies who spent years negotiating the 2015 agreement to fight global warming and pollution by reducing carbon emissions in nearly 200 nations. While traveling abroad last week, Trump was repeatedly pressed to stay in the deal by European leaders and the Vatican. Withdrawing would leave the United States aligned only with Russia among the world’s industrialized economies.

American corporate leaders have also appealed to the businessman-turned-president to stay. They include Apple, Google and Walmart. Even fossil fuel companies such as Exxon Mobil, BP and Shell say the United States should abide by the deal.

In a Berlin speech, Chinese Premier Li Keqiang said that fighting climate change is a “global consensus” and an “international responsibility.”

“China in recent years has stayed true to its commitment,” said Li, speaking in Berlin Wednesday.

Trump’s predecessor, President Barack Obama, enacted the deal without U.S. Senate ratification. A formal withdrawal would take years, experts say, a situation that led the president of the European Commission to speak dismissively of Trump on Wednesday.

Trump doesn’t “comprehensively understand” the terms of the accord, though European leaders tried to explain the process for withdrawing to him “in clear, simple sentences” during summit meetings last week, Jean-Claude Juncker said in Berlin. “It looks like that attempt failed,” Juncker said. “This notion, ‘I am Trump, I am American, America first and I am getting out,’ that is not going to happen.”

Some of Trump’s aides have been searching for a middle ground — perhaps by renegotiating the terms of the agreement — in an effort to thread the needle between his base of supporters who oppose the deal and those warning that a U.S. exit would deal a blow to the fight against global warming as well as to worldwide U.S. leadership.

That fight has played out within Trump’s administration.

Trump met Wednesday with Secretary of State Rex Tillerson, who has favored remaining in the agreement. Chief strategist Steve Bannon supports an exit, as does Environmental Protection Agency Administrator Scott Pruitt.

Trump’s chief economic adviser, Gary Cohn, has discussed the possibility of changing the U.S. carbon reduction targets instead of pulling out of the deal completely. Senior adviser Jared Kushner generally thinks the deal is bad but still would like to see if emissions targets can be changed.

Trump’s influential daughter Ivanka Trump’s preference is to stay, but she has made it a priority to establish a review process so her father would hear from all sides, said a senior administration official. Like the other officials, that person was not authorized to describe the private discussions by name and spoke only on condition of anonymity.

Interior Secretary Ryan Zinke said Wednesday in Alaska that he had “yet to read what the actual Paris Agreement is,” and would have to read it before weighing in.

Scientists say Earth is likely to reach more dangerous levels of warming sooner if the U.S. retreats from its pledge because America contributes so much to rising temperatures. Calculations suggest withdrawal could result in emissions of up to 3 billion tons of additional carbon dioxide in the air a year — enough to melt ice sheets faster, raise seas higher and trigger more extreme weather.

Associated Press writers Catherine Lucy, Michael Biesecker and Seth Borenstein in Washington and Lorne Cook in Brussels contributed to this report.
U.S. President Donald Trump confirms that the United States will withdraw from the 2015 Paris Agreement on climate change mitigation.