MELISSA BLOCK, HOST:
Voters in three states go to the polls tomorrow in North Carolina, Indiana and Ohio. It's the beginning of an eight-week stretch of primaries that should give us a good idea of how the political landscape is shaping up for this November.
NPR's political editor Charlie Mahtesian joins us now to talk about that. Hey, Charlie.
CHARLIE MAHTESIAN, BYLINE: Hi, Melissa.
BLOCK: And maybe the most closely watched primary tomorrow is going to take place in North Carolina. Republicans there will choose the nominee to take on the Democratic incumbent, Senator Kay Kagan. Tell us about this race.
MAHTESIAN: Well, Senator Hagan is widely viewed as one of the most vulnerable Senate Democrats this year, so the Republican race to take her on is turning out to be a pretty expensive and also high-profile affair. And if you were to measure it by the polls of the money spent, there are essentially three candidates to watch here, each of whom might be said to represent a distinct wing of the Republican Party.
There is state House speaker Thom Tillis who is the best funded Republican candidate. And he's also someone with support from the GOP with business and donor class. There's Gregg Brannon who hails from the Tea Party wing. And also there's Mark Harris who is a pastor with evangelical support.
And now, keep in mind that North Carolina is unusual in that a candidate needs to win at least 40 percent of the primary vote to avoid a runoff. So the key to watch here is whether the top finisher gets that 40 percent threshold tomorrow.
BLOCK: And as you say, a high profile primary. Some of the biggest, best known names in the Republican Party have taken a real interest in this race.
MAHTESIAN: Right, the North Carolina Senate race resembles a proxy war in the respects. Some of the Republican Party's top prospects for 2016, as well as several former presidential candidates, have already publicly chosen sides. And, in fact, just today Mitt Romney announced he's backing Thom Tillis. And so, by taking sides, Romney joins a handful of other Republican A-listers or marquee names like former Florida Governor Jeb Bush, Kentucky Senator Rand Paul, and former Arkansas Governor Mike Huckabee, all of whom have picked favorites here.
And so for endorsers like these names, a hotly contested primary like this offers a real opportunity to burnish their credentials by backing candidates who share the same values and priorities. It's also a pretty good way to build up some political chips as they move forward.
BLOCK: Right, Charlie, I gather there's another race in North Carolina that you've been paying some attention to.
MAHTESIAN: Of course. I can't help myself.
MAHTESIAN: Remember Clay Aiken, the "American Idol" runner-up from a few years ago back?
BLOCK: I do. I do.
MAHTESIAN: How can we forget him? Well, he's running for Congress as a Democrat this year. And it turns out that in addition to being a talented singer, he's a pretty decent candidate. But despite the great name recognition that he got from his showbiz career, he's not a lock to win. And in any case, if he does win the Democratic nomination tomorrow, it's still something of an uphill climb for him because he's going to be running in a pretty comfortable and safe Republican district.
BLOCK: Let's move over to Ohio. The speaker of the House, John Boehner, is on the ballot tomorrow. Anything that he should be worried about in this primary?
MAHTESIAN: I think it looks like speaker Boehner is in pretty good shape. He's got a handful of challengers but they're largely unknown. And just as important, they haven't spent much money on other campaigns. John Boehner, on the other hand, has been close to $12 million so far. So we're talking about a real David and Goliath dynamic here.
Still, I think it's going to be interesting to watch because we want to see how much of the Republican vote the speaker can capture, and what percentage is cast against him in protest. And I think anything less than a landslide win is going to raise eyebrows not just in Washington D.C., but also back home in Ohio.
BLOCK: Potentially setting up a leadership challenge for him in the House or no?
MAHTESIAN: Well, it certainly wouldn't work to his advantage to show some weakness back home in the district. But I think when you're talking about what happens in D.C., you're talking about a whole other area of support problems.
BLOCK: Let's pitch forward just a bit, Charlie, and talk about some of the other notable primaries that are on the horizon. What are you looking forward to?
MAHTESIAN: Well, tomorrow's primaries kick off a critical stretch of the election calendar. In two weeks, on May 20th, we're going to see one of the most important primary election days of the year, a time when we see a handful of top races in the nation take shape. That's the day, May 20th that is, that you'll see the outcome of the Tea Party primary challenge to Senate minority leader Mitch McConnell. And Georgia and Idaho, Oregon and Pennsylvania will also pick nominees in some very important and consequential House, Senate and governors' races.
BLOCK: OK. NPR's political editor Charlie Mahtesian. Charlie, thanks so much.
MAHTESIAN: Thank you, Melissa. Transcript provided by NPR, Copyright NPR.