First Read is a morning briefing from Meet the Press and the NBC Political Unit on the day's most important political stories and why they matter.

What Will Bernie Do?

After her victories over the weekend in Puerto Rico and the Virgin Islands, Hillary Clinton is now just 19 delegates away from hitting the 2,383 magic number of delegates needed to clinch the Democratic nomination. And since she’ll easily cross it before polls even close in California (126 pledged delegates are for up grabs in New Jersey alone on June 7), here’s maybe the most important question in politics over the next month: WWBD -- What Will Bernie Do? Does he continue fighting all of the way through July’s Democratic convention? “The Democratic national convention will be a contested convention,” Sanders declared on Saturday, per NBC’s Danny Freeman. Or does he bow out after tomorrow’s results? And bow out gracefully?

As one Capitol Hill Democrat closely observing the Clinton-vs.-Sanders race told us, “It’s absolutely going to be the difference between a positive, proactive summer of unity and one that will lead to the same location -- but travel across a much more treacherous path.” Indeed, an analysis shows that Sanders supporters climbing on board the Clinton Train turns a three-point race in the latest national NBC/WSJ poll (Clinton 46%, Trump 43%) into an eight-point Clinton lead (Clinton 51%, Trump 43%). So a lot is riding on what path Sanders chooses, as well as what happens in California tomorrow. Here’s the Democratic delegate math after last night:

In pledged delegates, Clinton currently holds a lead of 289 delegates (was 275 before last night)

Clinton 1,809 (54%)

Sanders 1,520 (46%)

Clinton must win 30% of remaining pledged delegates to get a majority in pledged delegates

Sanders must win 70% of remaining pledged delegates to get a majority in pledged delegates

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In overall delegates (pledged + super), Clinton holds an overall lead of 798 delegates (was 782 before last night)

Clinton must win 2% of remaining delegates to reach 2,383 magic number

Sanders must win 98% of remaining delegates to reach 2,383 magic number

Democratic U.S. presidential candidate Bernie Sanders speaks at a campaign event in Ventura, California, U.S. May 26, 2016. REUTERS/Jonathan Alcorn JONATHAN ALCORN / Reuters

Remember, rhetoric isn’t the best guide to determine how long a candidate will stay in the race

Given his rhetoric over the weekend, Sanders didn’t sound like someone ready to end the race as he took aim at the Clinton Foundation. “If you asked me about the Clinton Foundation, do I have a problem when a sitting secretary of state and a foundation run by her husband collects many millions of dollars from foreign governments, governments which are dictatorships? … Yes, I do,” he told CNN.

But remember, rhetoric isn’t always the best guide to determine how long a candidate will stay in the race. After all, Ted Cruz fired off some of his strongest arrows at Trump and the news media just 48 hours before he exited the 2016 GOP race. And around this same time eight years, as MSNBC’s Steve Kornacki has pointed out, Hillary Clinton was fighting Barack Obama over the Florida and Michigan delegations; campaigning aggressively in Puerto Rico, Montana, and South Dakota; and even invoking Bobby Kennedy’s assassination to explain why she was staying the race.

But while not conceding the night Obama crossed the Democratic magic number, Clinton was out of the race four days later. Yet also remember this: Bernie Sanders isn’t Hillary Clinton -- he wasn’t a Democrat until recently, he won’t be running for president again, and he and his supporters have claimed that the Democratic contest has been rigged.

GOP leaders’ awkward dance with Trump

Turning to the Republican race, it’s striking how Republican leaders are both 1) embracing Trump and hoping he wins, and 2) criticizing his controversial comments, especially his recent remarks that a federal judge is biased against him because he’s Mexican-American. Here was Senate Majority Leader Mitch McConnell on “Meet the Press” yesterday:

CHUCK TODD: You know what he has said about this federal judge that's overseeing the Trump University lawsuit. He has essentially said he cannot be impartial because he's Hispanic. Is that not a racist statement?MCCONNELL: I couldn't disagree more with a statement like that.CHUCK TODD: Is it a racist statement?MCCONNELL: I couldn't disagree more with what he had to say.CHUCK TODD: Okay. But do you think it's a racist statement to say?MCCONNELL: I don't agree with what he had to say. This is a man who is born in Indiana. All of us came here from somewhere else. Almost all Americans are either near term immigrants, like my wife, who came here at age eight, not speaking a word of English, or the rest of us is ancestors were risk takers, and who got up from wherever they were and came here and made this country great. That's an important part of what makes America work.

And here was Senate Foreign Relations Committee Chairman Bob Corker, who’s considered a VP possibility for Trump: “Look, I don't condone the comments. And we can press on to another topic. I think we have to move beyond that and I think he has a tremendous opportunity to disrupt the direction that Washington is moving in and create tremendous opportunity. And I hope he's going to take advantage of that and I think that he will.”

Trump: It’s possible a Muslim-American judge would be biased against me, too

Over the weekend, CBS asked Trump if a Muslim judge would also be biased against him, due to Trump’s proposal for a temporary ban on Muslims entering the United States. Trump’s answer: "It's possible, yes. Yeah. That would be possible, absolutely.”

Dysfunction inside the Trump campaign

Meanwhile, MSNBC’s Benjy Sarlin and NBC’s Ali Vitali and Kay Tur have filed this report on the dysfunction inside the Trump campaign: “Republicans working to elect Trump describe a bare bones effort debilitated by infighting, a lack of staff to carry out basic functions, minimal coordination with allies, and a message that’s prisoner to Trump’s momentary whims... Veteran operatives are shocked by the campaign’s failure to fill key roles. There is no communications team to deal with the hundreds of media outlets covering the race, no rapid response director to quickly rebut attacks and launch new ones, and a limited cast of surrogates who lack a cohesive message.” But the New York Times is reporting (and NBC has confirmed) that Trump has hired a new top aide (a veteran from Bob Dole’s 1988 and 1996 presidential campaigns) and hopes to bring in at least two new communications staffers.

On the trail

Hillary Clinton campaigns in the Los Angeles area, including a 10:00 pm ET concert at the Greek Theatre…. Bernie Sanders holds his final California rally/concert in San Francisco at 8:00 pm ET. Don’t forget to check out the political unit’s rolling minute-to-minute coverage of all the latest 2016 developments at the On the Trail liveblog at NBCNews.com.