AUDIE CORNISH, HOST:
The presidential race has been dominating political news, but control of the Senate is also up for grabs this year. And that fight will help determine what a President Trump or Clinton can actually get done in office. Republicans are defending more than twice as many Senate seats as Democrats, but Democrats have to pick up quite a few seats if they want control of the Senate back. NPR political reporter Jessica Taylor is following this year's congressional contests. And, Jessica, to start, how difficult is it? Like, what is this road for Democrats to take back the Senate?
JESSICA TAYLOR, BYLINE: Both the map and the math is in their favor. Republicans are defending 24 seats to Democrats just 10, and most of those the Republicans are defending are in presidential swing states like Pennsylvania, Florida, North Carolina, Ohio. And so they need to get five to flip it or just four and - to win the White House. And that's absolutely doable for them, especially in an election year like this where turnout already favors Democrats.
CORNISH: So we're already talking about battleground states. So then how much does the presidential race affect what's going on in these Senate contests?
TAYLOR: Presidential years are about the top of the ticket, so the Republican nominees there are tied to their party's nominee whether they like it or not. And with a candidate like Trump, we're seeing them have to distance themselves, especially in the wake of many of the controversial things he said just this week. Probably the most vulnerable incumbent senator is Mark Kirk in Illinois. He sits in the bluest state that a Republican defends. He was the first incumbent to come out and say, I am not going to vote for Donald Trump. He withdrew his endorsement, and he's even touting that in an ad. Here, let's listen.
(SOUNDBITE OF POLITICAL AD)
UNIDENTIFIED WOMAN: Mark Kirk bucked his party to say Donald Trump is not fit to be commander in chief. Mark Kirk - courageous and independent.
MARK KIRK: I'm Mark Kirk and I approve this message.
TAYLOR: But for other Republicans, you know, Trump's gone on the attack against them if they haven't come to bat for him, like he did yesterday in an interview with The Washington Post hitting New Hampshire Senator Kelly Ayotte. Ayotte's tried to sort of walk a delicate line. She said she supports her party's nominee, but doesn't endorse him. And she had a blistering statement against Trump after what he said about Captain Khan's parents. But for someone like Ayotte, I think that's a benefit for her. She can use that and say, look, I'm different from Donald Trump, and he's even attacking me for that.
CORNISH: Now, are there any surprises? Races that weren't on the radar before but have suddenly become a lot more interesting?
TAYLOR: I think there are two states that we didn't expect to maybe factor in as much. The first - Republicans got a big break earlier this year in Florida, where initially Marco Rubio was running for president. He said he's not going to run for re-election regardless of what happened in the primary. He changed his mind at the last minute, and he is back in. And that's a seat where I think without Rubio, they really wouldn't have much of a chance. Now, he's in a primary later this month against a wealthy homebuilder who has a similar profile to Donald Trump, in a way, Carlos Beruff, who has attacked him for being too much of the establishment. And he has to survive that first. But if he does that I think he's pretty well-positioned to hold that.
And then the second one is Indiana, where - which we weren't talking about at all to begin with. You have Dan Coats, who is retiring. This wasn't really on their radar at all until Democrats convinced the nominee there to drop out and for former Senator Evan Bayh to run again. So he has really sort of put this race back into play because of this.
CORNISH: So those are the surprises. What are the races you're going to be watching that could signal a tipping of the balance in November?
TAYLOR: Yeah, if we're talking about places like Missouri being in play, where Republicans are worried about - that Democrats have a very strong recruit there, if Arizona with John McCain - if we're talking about him being in a very competitive race where he does have a very tough challenge there if he survives his primary - North Carolina, on down the ballot, places like this - if we're talking about those possibly flipping then I think it becomes even more of a headache for Republicans to try to hold on.
CORNISH: That's NPR political reporter Jessica Taylor. Jessica, thanks so much.
TAYLOR: Thanks, Audie. Transcript provided by NPR, Copyright NPR.
