By CLAIRE GALOFARO and MARTHA IRVINE
AP National Writers

JEFFERSONVILLE, Ind. (AP) - More than 30 million Americans already have voted in a midterm election expected to draw unprecedented numbers by the time polls close Tuesday night. In casting their ballots for House and Senate races, voters will render a verdict on President Donald Trump's tumultuous tenure, deciding whether his 2016 election was a one-off or if his divisive style of governing will define the future of American politics.

Trump has sought to fire up his base in recent weeks by putting the spotlight on a caravan of Central American migrants that he calls "an invasion" of criminals and terrorists. Among some Republican voters, that message is resonating. But many Trump opponents see the election as a chance to reject that kind of rhetoric and turn the country around.

Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.