Americans Prepare to Render Midterm Verdict on TrumpA sharply divided U.S. electorate heads to the polls Tuesday to elect a new Congress and to render a midterm verdict on President Donald Trump. The results could shift the balance of power in Washington and alter the next two years of Trump's presidency. All 435 seats in the House of Representatives are at stake Tuesday, plus 35 of the 100 U.S. Senate seats and 36 of the 50 state governorships. Public opinion polls and analysts suggest that opposition Democrats have an advantage in the battle for control of the House of Representatives. Democrats are favored to win more House seats than they currently have and they need an overall gain of 23 to retake the House majority. Republicans are counting on Trump to rally his supporters in the closing hours to help maintain their narrow 51-to-49 seat edge in the Senate. Twenty-six of the 35 Senate seats at stake are held by Democrats and nine are held by Republicans. Immigration focus Democrats are trying to hold 10 Senate seats in states where Trump prevailed in the 2016 election, including Tennessee. Trump blasted Democrats over immigration during a recent rally in Chattanooga. "Democrats want to invite caravan after caravan of illegal aliens to pour into our country. I don't think so," Trump said, invoking images of the caravan of Central American migrants moving through Mexico. "No nation can allow its borders to be overrun. And that is an invasion. I don't care what they say. I don't care what the fake media says. That is an invasion of our country." Democrats feel increasingly optimistic about their chances of taking back control of the House. Last week, Democratic House leader Nancy Pelosi predicted it would happen. Democrats are getting some high-profile campaigners to help them, including former President Barack Obama, who rallied voters in his home state of Illinois. "When you vote, Illinois, you can reject that kind of politics. When you participate in the political process, you can be a check on bad behavior. When you vote, Illinois, you can choose hope over fear," he said. Early turnout has been huge in several states, especially for a midterm election when total voter turnout often struggles to reach 40 percent of eligible voters. Trump a central issue Polls show Democrats are most concerned with health care and the economy, with Republicans focused on immigration. But Brookings Institution expert John Hudak said it is also clear that Trump is a major issue for both parties this year. "This is a president who wants this midterm to be a referendum on him, largely because he thinks his own popularity is so great that it will carry Republicans across the finish line," Hudak said. But Trump is not only battling Democrats in this year's election, he is also battling history. "The big picture is that midterm elections go against the president's party," noted John Fortier of the Bipartisan Policy Center in Washington. "I think there will be no difference here. The Democrats will do quite well in the House of Representatives, in the governorships and state legislatures." Trump's approval rating is also a concern for Republicans. RealClearPolitics puts Trump's average approval at about 43 percent, with 53 percent disapproving. "The midterm history is pretty stark in that the president's party usually loses ground in the midterms and it is usually a question of how much ground they lose," said University of Virginia analyst Kyle Kondik. "That is particularly true when a president is unpopular, as this president is." Kondik notes that in the 29 congressional midterm elections held since 1900, the president's party has lost House seats in all but three — 1934, 1998 and 2002. Will Democrats turn out? Historically, though, Republicans are more reliable voters in midterm elections. Gallup pollster Frank Newport said that puts pressure on Democrats to make sure their supporters get out and vote. "Under the expectation that Republican voters typically are more likely to turn out, can Democrats energize people who identify with the Democratic Party to turn out and vote for their candidates?" Newport said. If Democrats win enough House seats to reclaim the majority, Trump would face a shift in the balance of power in Washington. "The House has been a rubber stamp for the Trump agenda. It will no longer be a rubber stamp," said Jim Kessler of the centrist Democratic group Third Way. "Anything that gets done will have to be a bipartisan basis." Democrats are hoping for a wave election that would bring them control of the House and gubernatorial victories in key states like Florida, Ohio and Wisconsin. Republicans are counting on Trump's frenetic campaign pace in the final days to help them retain or even expand their narrow Senate majority.