ROBERT SIEGEL, HOST:
Donald Trump is set to announce his vice presidential pick tomorrow morning in New York City. The official line from the Trump campaign is that no final decision has been made, but there are lots of signs that he's leaning to Indiana's Republican Governor Mike Pence. Pence is one of several potential running mates who have campaigned with Trump recently in the kind of reality-TV-auditioned tour. Here's Trump with Pence in Indiana earlier this week.
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DONALD TRUMP: I often joke. You'll be calling up Mike Pence. I don't know whether he's going to be your governor or your vice president - who the hell knows?
SIEGEL: So if it is Pence for VP, What does that mean? NPR national political correspondent Mara Liasson is here. Hi, Mara.
MARA LIASSON, BYLINE: Hi, Robert.
SIEGEL: If Mike Pence is Donald Trump's pick, what does that choice say?
LIASSON: Well, if it is Mike Pence, it would tell us that Trump is capable of doing something very un-Trump like. And he did - if that's his choice, it turns out he didn't follow his gut, which is an approach he said has always worked for him in the past. This time, he will have done the traditional thing. He will have followed the advice of his campaign chairman Paul Manafort, his new adviser Kellyanne Conway, who previously worked for Pence, and his children who thought Pence was the best pick and the Republican establishment, who given the choices of Newt Gingrich, Chris Christie and Pence were most comfortable with Pence, thought he would be the most unifying pick.
So if picking a vice president is the first presidential-level decision that a candidate makes, this tells us that Trump can take advice, and he can act like a traditional candidate at least occasionally.
SIEGEL: All right. If it is Pence...
LIASSON: If it is (laughter).
SIEGEL: And we don't know that for a fact. What virtues would Pence bring to the ticket as a running mate?
LIASSON: The first thing he does is he does no harm, and that's the most important criteria. He is very popular with the Christian conservative base of the party. He is a calm, serious candidate. He's not bombastic or provocative, compared to what was reported to be Trump's other two top choices - Chris Christie and Newt Gingrich. Both of them have huge Trump-sized personalities, but they also have a lot of baggage.
SIEGEL: Well, vice presidential nominees often play the role of attack dog going after the opposing presidential candidate. Is Governor Pence suited to a role like that?
LIASSON: That's a good question. He is very soft-spoken. He certainly wouldn't be an attack dog like Newt Gingrich or Chris Christie would have been. Those two figures really relish the role of antagonist. But Pence showed that he can attack Hillary Clinton as required when he was campaigning with Donald Trump in Indiana earlier this week on his kind of reality TV tryout tour. Also, he will have to do what many vice presidential candidates have to do which is reconcile his past criticisms of Donald Trump. Pence had endorsed Ted Cruz. He had - has been described during the primaries as loathing Donald Trump. He said Trump's call to ban Muslims was offensive and unconstitutional.
He supported the Trans-Pacific trade deal. And he took the Obamacare Medicaid expansion in Indiana. All those things he's at odds with Trump on, but this is really par for the course for...
SIEGEL: We've seen vice presidential candidates...
LIASSON: ...Vice presidential candidates, sure, sure...
SIEGEL: Learn to undo more positions than...
LIASSON: That's right. And all this being said that Trump could wake up tomorrow morning and say, you know what? My gut tells me to go with Chris Christie, and let's just change course altogether. So this is all speculative, but all the signs in the tea leaves seem to be pointing to Pence.
SIEGEL: And very interesting. Mara Liasson, NPR's national political correspondent, thanks.
LIASSON: Thank you. Transcript provided by NPR, Copyright NPR.