ARI SHAPIRO, HOST:
Last night in South Carolina, congressional candidate Katie Arrington defeated a Republican incumbent and summed up what her victory meant.
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KATIE ARRINGTON: We are the party of President Donald J. Trump.
SHAPIRO: The president is defining the midterm campaign in many ways. And the message Republican voters are sending is clear, support Trump or else. NPR national political correspondent Mara Liasson is here with some insights. Hi, Mara.
MARA LIASSON, BYLINE: Hi, Ari.
SHAPIRO: Last night, Republican Congressman Mark Sanford lost his primary. He was attacked by his opponent for having criticized Trump. How much should we take away from that?
LIASSON: I think we should take a lot. I think that it shows that former House Speaker John Boehner was probably right when he said there is no Republican Party right now. There's a Trump party, but the GOP is off taking a nap somewhere. Mark Sanford lost his primary. He was a conservative Republican who has not voted against Trump on policy, but he has criticized him. So the most important factor in these Republican primaries is becoming how personally loyal, how devoted are you to Donald Trump?
You just heard Katie Arrington at her victory party. Last week in Alabama, Martha Roby, a conservative Republican, was forced into a runoff election after a primary battle, which centered around who is more devoted to Trump. Roby famously unendorsed Trump during the 2016 campaign after the Access Hollywood tape came out and she was personally offended. And this is what Bob Corker, the senator from Tennessee, has been talking about. Today, he told reporters in the Capitol that the Republican Party has turned into a cult. What he means is a cult of personality that's based not on issues just on loyalty to Donald Trump.
SHAPIRO: And last night was also a good primary night for another Trump booster who some Republican leaders really don't seem very happy about in Virginia.
LIASSON: That's right. Corey Stewart won the Republican primary for Senate. He's going to go up against the Democratic incumbent Tim Kaine. He had been the co-chairman of the Trump campaign in Virginia in 2016. He was fired by the campaign because he protested in front of the RNC because he thought they were insufficiently supportive of Trump. He's also a candidate who is closely identified with the movement to preserve Confederate statues, Confederate heritage.
He's posed with the Confederate flag many times. And what's really interesting is the NRSC, the National Republican Senatorial Committee, the campaign committee of the Senate, has chosen not to support him, even though the president is. And Democrats in Virginia are happy about this. They are hoping that having Corey Stewart at the top of the ticket in Virginia will drag down other Republican candidates in House races because he will turn off moderate Republican voters and he won't bring them out to vote.
SHAPIRO: You mentioned Senator Bob Corker, Republican of Tennessee. He gave a pretty extraordinary speech on the floor of the Senate yesterday. Let's listen to how he criticized his GOP colleagues here.
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BOB CORKER: Gosh, we might poke the bear, is the language I've been hearing in the hallways. We might poke the bear. The president might get upset with us.
SHAPIRO: So it sounds like there is some dissent within the GOP.
LIASSON: There's some dissent. What Corker was talking about is people are afraid that they'll end up in the minority if they cross Trump or criticize him. Corker was trying to get an amendment on a bill that would have taken some of Trump's tariff power away from him. Corker has talked about the willingness to spend political capital, in other words, to do something you believe in even if it might cost you votes. But Corker himself is retiring. In other words, he is only saying all these things after he's decided to retire.
So you see this all over the place, not just on the campaign trail, also in the House. There was a revolt on immigration from moderates. They wanted a vote on some bills on the floor, but they capitulated. So I think there's been a complete and total takeover by Trump of the Republican Party, not just changing their views on trade and immigration and Vladimir Putin...
LIASSON: ...But also, he's made them very reluctant to criticize him at all.
SHAPIRO: NPR's Mara Liasson, thank you.
LIASSON: Thank you. Transcript provided by NPR, Copyright NPR.