ROBERT SIEGEL, HOST:
Ted Cruz is successfully wooing delegates even in states where Donald Trump won primaries. Here's why. If the national convention ends up being open or contested, delegates can eventually switch their allegiance, and that's causing some fights.
Take Georgia. Trump won that state's primary, but when some of his hard-core supporters weren't chosen as delegates at a local meeting on Saturday, they grabbed the American flag, and they stormed out. Florida is also seeing this tension, as NPR's Greg Allen reports.
GREG ALLEN, BYLINE: In most states, delegates are bound to candidates through at least the first round of balloting at the Republican convention in July. Who serves as delegate only becomes important if Trump doesn't win enough delegates - 1,237 - to secure the nomination on the first ballot. Campaigning in New York yesterday, Trump once again blasted the delegate's selection process.
(SOUNDBITE OF ARCHIVED RECORDING)
DONALD TRUMP: I think we're going to win the 1,237. I think we're not going to have the second ballot. I just tell you, though. Despite what I just said, it's a corrupt system, and it's a rigged system.
ALLEN: In an interview on Fox News, Trump's campaign manager, Corey Lewandowski, aimed his fire at Florida's Republican chairman who he said was biased against Trump. But in Florida, it's not the party chairman but local officials who select the large majority of delegates.
Delegate selection - three for each of the state's 27 congressional districts - has been going on here for nearly a month. On Saturday, 150 perspective delegates turned out at an industrial park in Hialeah, a Miami suburb.
ALLEN: Fifteen delegates were being selected from congressional districts in Miami-Dade and surrounding counties. In Florida, the state's 99 delegates are all bound to vote for Trump through first three rounds of balloting. In the past, party official Scott Hopes says who serves as delegate has drawn little interest because the position has been largely ceremonial - not this year.
SCOTT HOPES: You know, the campaigns are already, you know, heavily campaigning and lobbying those delegates in anticipation of the convention going to a fourth round.
ALLEN: Miami-Dade was the only county in Florida Trump didn't carry in last month's primary. Local favorite Marco Rubio won here. If there's a contested convention and one that goes to a fourth round of balloting, Ozzie Torres, a member of the Miami-Dade Republican Executive Committee, says he thinks Florida's delegates may have a lot of influence, and he expects they'll vote as a bloc.
OZZIE TORRES: Sure, I mean, I think there's going to be a Florida caucus, if you will. And then I think - you know, I'm sure weâll work as a team for what we think would be the best move as far as for the party as a whole for the general, so...
ALLEN: It's Republican Party leaders in Florida who decide mostly behind closed doors who the delegates will be, and that's left Trump supporters complaining that they've been shut out of the process.
UNIDENTIFIED CROWD: (Chanting) Stop the steal. Stop the steal. Stop the steal.
ALLEN: In Hialeah, about a dozen Trump supporters gathered across the street from where delegates were being selected. The chairperson of the Trump campaign in nearby Broward County, Dolly T. Rump - yes, that really is her name - had applied to be a delegate there earlier this month but was turned down.
DOLLY T. RUMP: The decision makers in the room - most of them were establishment, and so therefore most of those that were selected, I would say seven I know for sure were not Trump supporters, and the other two are questionable.
ALLEN: Rump says the way they have been selected, Trump likely won't have the support of Florida delegates if balloting goes beyond three rounds. The process has left Trump supporters like Juan Fiol frustrated.
JUAN FIOL: I mean, who needs all this ballot and all this backroom closed-door BS?
ALLEN: Fiol applied to be a delegate representing Miami but was disappointed, and he echoed his candidate, Donald Trump. Fiol said he doesn't think the Republican Party is treating Trump fairly and warned there could be consequences.
FIOL: They keep talking about him not being loyal to the party. The party is not loyal to their constituents, and their constituents are going to leave them for a third party if they're not careful.
ALLEN: If he wins big tomorrow and in other upcoming contests, Trump still has a path to that magic number, 1,237, and the Republican presidential nomination. If he doesn't get there, who the delegates are and how they were selected will matter a lot. Greg Allen, NPR News, Miami. Transcript provided by NPR, Copyright NPR.