ARI SHAPIRO, HOST:
It is Tuesday, and it is super. That's because 1 in 4 Americans have their say in the presidential nominating contests today, casting ballots or attending caucuses in 13 states. Roughly, a quarter of the total delegates are at stake in each party tonight. This is the biggest night of the season, and joining us to talk about what it all means is NPR national political correspondent Mara Liasson. Hey, Mara.
MARA LIASSON, BYLINE: Hi, Ari.
SHAPIRO: Let's start with the Democrats. What is at stake politically for Hillary Clinton and Bernie Sanders tonight?
LIASSON: What's at stake tonight is, for Bernie Sanders at least, he has a chance to catch up or at least set himself up to catch up to Hillary Clinton. There are a lot of states voting tonight in the South that look like South Carolina, and that is where Hillary Clinton beat Bernie Sanders among African-American voters by something like 85 to 14. So he has a chance to prove that he can do better with African-American voters, but he's also looking to actually win states which have more white voters, like Minnesota, Massachusetts, Oklahoma, his home state of Vermont. If he doesn't do that, her lead gets pretty insurmountable pretty quick.
SHAPIRO: We've talked so much this year about the way the race has reshaped the Republican Party. What about the Democratic Party? What has the race done to the party so far?
LIASSON: Well, one thing Democrats told us from the very beginning is they didn't want a coronation of Hillary Clinton, and they didn't get one. And even though Sanders, while perhaps not igniting the political revolution that he's calling for, he did move Hillary Clinton to the left. He moved her to the left on trade, on Keystone pipeline, to a certain extent on Social Security. We also learned that Democrats are not as excited about this election as Republicans. Democratic turnout in state after state after state has been down compared to 2008 levels. And then other big question we were waiting to find out the answer to was whether the Obama coalition would turn out without Obama on the ticket, and that is young voters and minority voters. What we learned is that African-Americans will show up; young voters, not so much. They voted largely for Bernie Sanders, but they didn't show up in huge numbers.
SHAPIRO: OK, let's turn to the Republicans. To hear candidates and party officials tell it, tonight is an existential moment for the GOP. Is this their last chance to slow down Donald Trump?
LIASSON: I think it is because the Republican National Committee wrote some rules this year to help a frontrunner consolidate his support and wrap up the nomination sooner than the dragged out contest that Mitt Romney had to go through last time. And these rules worked only too well, it turns out, for Donald Trump. So tonight you have Ted Cruz, if he's going to slow down Donald Trump, having to win his home state of Texas. Marco Rubio, if he can win a state, he's looking to maybe Colorado or Massachusetts or Minnesota. But at the very least to slow down Donald Trump, Ted Cruz and Marco Rubio have to get over the 20 percent threshold that many states require to get any delegates because if Donald Trump, for instance, is the only candidate that gets over 20 percent in a state, he gets everything.
SHAPIRO: The Republican Party establishment seems to be struggling so much here. What risks and rewards are elected officials considering as they look at Donald Trump's campaign?
LIASSON: Well, there's a wide range of reactions and accommodations to Donald Trump in the Republican Party. You've got Paul Ryan, the speaker of the House, desperately trying to make a distinction between the Congressional Republicans and Donald Trump. He condemned Trump for not being quick enough to disavow the support of KKK leaders. You've got Republicans who are endorsing Donald Trump. You've got Senator Jeff Sessions and New Jersey Governor Chris Christie. You have several House members. Then you have Republicans talking about breaking off and forming a third party - an alternative conservative party. Now, we're a long ways away from that, but the bottom line is the Republican establishment remains completely flummoxed by Donald Trump.
SHAPIRO: And do you think that means a brokered convention is a real possibility on the Republican side?
LIASSON: There's no such thing as a brokered convention anymore 'cause there are no brokers to go into a smoke-filled room and broker anything. But there could be a contested convention, which means that Donald Trump wouldn't get 1,237 delegates on the first ballot. And after the first ballot, delegates are unbound. So the idea is, or the questions for Republicans - if, for some reason, they could deny Trump the nomination on the second or third ballot, what would be the reaction of Donald Trump to that? And what would be the reaction of his supporters? We're going to know tonight whether a contested convention is more of a possibility or not depending on how many of the 600 or so delegates Donald Trump gets.
SHAPIRO: Lots more to come from NPR national political correspondent Mara Liasson. Thanks, Mara.
LIASSON: Thank you. Transcript provided by NPR, Copyright NPR.
