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The Republican Party has controlled the U.S. House of Representatives since the tea party wave of 2010. That control has not been in doubt until recently because of Donald Trump. NPR congressional reporter Susan Davis reports on how his rise could shake up Congress.
SUSAN DAVIS, BYLINE: The prospect of Donald Trump at the top of the ticket has raised a question on Capitol Hill that six months ago no one was asking - could Democrats take over the House this year? Washington Democrat Denny Heck runs candidate recruitment for his party. He puts Democrats' chances this way.
DENNY HECK: Everybody knows that Democrats in the House are going to gain seats this time, and it's just a question - how many? Even the Republicans will candidly admit that in private. But now we believe that our opportunity to pick up more is greater as a consequence of the, quote, "Trump factor."
DAVIS: That Trump factor, Heck says, could make competitive districts with three specific kinds of voters that find Trump most offensive.
HECK: High education levels, high numbers of white-collar jobs or high numbers of Hispanics - any one of those would put in play some districts that otherwise we might have been in but are a little more enthused about now than we were before.
DAVIS: And Democrats are favored to pick up seats. Their party historically performs better in presidential election years. But Democrats haven't been favored to win a majority since Republicans swept control six years ago. House Republicans are divided over whether Trump helps or hurts their races. On one side, our Republicans like South Florida Congressman Carlos Curbelo. His district is 70 percent Hispanic, and he thinks Latino voters will overwhelmingly oppose Trump this November.
CARLOS CURBELO: I don't think the American people are going to respond well to someone who is so divisive and offensive to many voters.
DAVIS: Curbelo has pledged to vote against Trump even if he's the nominee. But on the other side are Republicans like New York's Tom Reed. Reed says Trump's message opposing free trade pacts and bringing back manufacturing jobs resonates with voters in his swing district. And that's why Reed last week became the first Republican in a competitive House race this year to endorse Trump. He doesn't buy the talk that Trump has no appeal beyond his core base of white working-class voters.
TOM REED: He's defying the laws of political gravity, and I think we're going into uncharted waters here. And when we especially get to uncharted waters, that's where the collective wisdom of the people is something I'm really sensitive to because I trust that wisdom.
DAVIS: Pennsylvania's Lou Barletta agrees with Reed. He also endorsed Trump last week and has zero doubt that Trump will win Pennsylvania and help down ballot Republicans there. Barletta says Trump is not limiting the GOP's reach. He's redefining it.
LOU BARLETTA: I think Donald Trump brings more Democrats and independents to the Republican Party. And I think this is an opportunity to have a new Republican Party made up of working men and working women, and we should be embracing that rather than trying to push away.
DAVIS: To be clear, the math for Democrats is daunting. Republicans have their largest majority in nearly a century, and Democrats would need to pick up at least 30 seats for a takeover. The Cook Political Report, a nonpartisan election forecaster says Democrats would need to win 97 percent of Republican seats currently in play. That's why House Speaker Paul Ryan swatted down a question about whether Trump puts his majority at risk. He says Republicans' only concern is putting together a fresh policy agenda.
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PAUL RYAN: I'm not concerned about the House flipping because we are in control of our own actions, and that means we are putting together an agenda to take to the country to show what we need to do to get this country back on the right track.
DAVIS: The question for Democrats is whether they can put enough candidates on the field to capitalize if the Trump factor goes their way. Susan Davis, NPR News, Washington. Transcript provided by NPR, Copyright NPR.