US Lawmakers: Flynn Had to GoU.S. lawmakers of both political parties said they approved of Michael Flynn’s resignation as national security adviser and urged President Donald Trump to bring order to his fledgling White House on national security matters and beyond. “That was a decision that was certainly warranted,” Republican Senator John McCain of Arizona told reporters Tuesday. “The vice president was misinformed [by Flynn].” In his resignation letter, Flynn said he gave Vice President Mike Pence incomplete information about his conversations with Russia’s ambassador to the United States. Pence went on national television to deny that U.S. sanctions had been discussed with the Russian envoy, but Flynn later conceded that the issue may have come up. U.S. law bars unauthorized citizens from negotiating with foreign governments. Independent Senator Angus King of Maine noted that Flynn spoke with the Russian ambassador during the waning days of the Obama administration. “Private citizens, which is what general Flynn was at that point, are not supposed to be negotiating with foreign countries,” King said. “We can only have one president at a time.” Overarching concerns Lawmakers said their concerns go beyond Flynn’s actions. “He [Trump] has to have a proper decision-making process,” McCain said. “There are various centers of influence in the White House that lead to a degree of disarray and disorganization, the likes of which we have never seen.   Our [congressional] oversight responsibilities are increased now because it’s pretty clear that this administration is incoherent on national security,” he added. “He [Trump] has to select a national security adviser,” said Democratic Senator Jack Reed of Rhode Island. “That’s step one. Step two, he has to, I think, conduct a very thorough review of his relationship with his associates and the Russians. And there are many suggestions that those associations are more than just casual.”   Flynn's resignation adds to a slew of controversies concerning Russia and underscores the need for thorough congressional probes, Democratic Senator Joe Manchin of West Virginia said. “This is very alarming,” Manchin told VOA. “We will find out the depth of that [Russian influence] and where it goes, wherever the facts take us. You want a conclusion to this, if it goes any further, any deeper. I think the public wants to know and has a right to know, and we’re going to look at it.” Further investigation? But just hours after Flynn resigned, House Republicans showed limited interest in opening up new investigative avenues to pursue lingering questions about the Trump administration's links with Russia. "I'm not going to pre-judge any of the circumstances until we have all the information," House Speaker Paul Ryan told reporters in his weekly press briefing Tuesday morning. Ryan said he would leave it up to the Trump administration to describe the circumstances leading to Flynn's resignation. "National security is perhaps the most important function or responsibility of a president and I think the president made the right decision to ask for his resignation. You cannot have a national security adviser misleading the vice president," Ryan said. WATCH: Ryan says Flynn 'Lost the President's Trust' No media source currently available "I think that the situation is taking care of itself," House Oversight Committee Chair Jason Chaffetz told reporters after the weekly Republican conference meeting. Chaffetz said the matter was better handled in the ongoing House and Senate Intelligence Committee investigations on Russian election interference rather than in his own oversight committee. "It's not something that the oversight committee can actually look at because sources and methods are the exclusive purview of the intel committee," Chaffetz said. Earlier in the day, Congressman Devin Nunes, the chair of the House Intelligence Committee, said his committee would focus on investigating the leaks that revealed Flynn's discussions with the Russian ambassador. Independent investigation But House Democrats demanded answers to the questions they say were raised — not resolved — by Flynn's resignation, calling for an independent body to examine what Trump knew about Flynn's contact with Russia and when he knew it. Ranking Intelligence Committee Chair Adam Schiff said Americans should be deeply concerned the Trump administration asked for Flynn's resignation only after the news of his calls had leaked to the public and called for a thorough investigation into links between the Trump campaign and Russia. WATCH: Schiff Says White House 'Misled' Americans No media source currently available "The administration was OK with the fact that the American people were laboring under the falsehood that they had not discussed the sanctions with the Russians," Schiff said. "If the speaker won't commit to a Congressional probe, he should allow for an independent commission and get out of the way," he continued. And while many House Democrats used language recalling the threatened impeachment and eventual resignation of President Richard Nixon more than 40 years, they said the calls for investigation into the Trump administration were about more than partisan politics. "We are in a fight for the soul of our democracy," said ranking member of the House Oversight Committee Congressman Elijah Cummings. "Republicans need to join us. It's not a Democratic issue, a Republican issue, it's not an independent issue. It's an American issue."