President Trump held rallies in Ohio, Indiana and Missouri the day before the vote: Getty Images
US voters decide Tuesday whether President Donald Trump will keep his Republican majority in Congress or face a hostile Democratic majority after a bitter campaign for midterm elections described by both sides as a battle for America's soul.
For almost two years, Trump's rule-breaking, sometimes chaotic administration has enjoyed a largely free hand from the twin Republican-controlled chambers, but the midterms could finally see his wings clipped, reports AFP.
The entire 435-member House of Representatives and a third of the 100-seat Senate are up for grabs.
According to nearly all pollsters, the Democrats have a good chance of winning the House, while the Republicans are likely to retain the Senate.
But with turnout a key unknown factor and pollsters still unsure about the effect of Trump's maverick style on voters, both parties admit that they may be in for nasty surprises.
After a campaign in which Trump was accused of race-baiting with repeated and unsubstantiated references to an "invasion" of undocumented immigrants bent on rape and murder, left-right divisions in America could not be deeper.
Although not on the ballot, Trump made himself the focus of the entire contest, jetting around the country to hold rallies, including in three states on Monday alone.
Trump declared "the Republican agenda is the American dream" and at his final event, in Cape Girardeau, Missouri, he called on supporters to seize their "righteous destiny as Americans. "
Democrats saw the election in equally historic terms.
Voters will "define the future, not just of Texas, but of this country, not just of this generation but every generation that follows," said Democrat Beto O'Rourke, who is challenging Senator Ted Cruz in traditionally deep-Republican Texas.