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.

Defiant Sanders threatens Democratic unity

Remember when it was the Republicans who had a unity problem? Well, consider the events and actions of the last four days on the Democratic side. On Saturday, Bernie Sanders’ supporters revolted at the Nevada state Democratic convention -- all over a caucus process Hillary Clinton originally won in February, 53%-47%. Afterwards, the state party chairwoman recounted receiving death threats and vile messages. On Tuesday, Sanders released a statement doubling down on the Nevada protest: Although he said he condemned violence and harassment, he didn’t apologize and accused “the Democratic leadership” of using “its power to prevent a fair and transparent process from taking place.” And last night, after his narrow apparent loss in Kentucky and win in Oregon, Sanders struck a defiant tone at his rally in California, challenging the Democratic Party. “The Democratic Party is going to have to make a very, very profound and important decision,” he warned. And per NBC’s Danny Freeman, the crowd booed mentions of the party and chanted, “Bernie or Bust” repeatedly. After Clinton’s win in New York last month, we wondered how Sanders would land his plane given Clinton’s near-insurmountable lead in the delegate race. Well, the plane is now experiencing some serious turbulence. Will he be Sully Sullenberger? Or a kamikaze pilot?

However, the Dem race could look much different to Sanders and his supporters come June 8

But don’t forget: In May of 2008, Hillary Clinton was reminding Democrats that Bobby Kennedy was assassinated in June, which offended Barack Obama’s campaign and supporters. (They took that to mean that Clinton was continuing to campaign because Obama might get assassinated; Clinton later said she regretted her words.) And after Obama was declared the “presumptive Democratic nominee” on June 3, 2008, Clinton vowed to campaign on. But the ground shifted days later, and Clinton eventually bowed out of the race and endorsed Obama. The same scenario COULD take place after June 7, when Clinton is guaranteed to cross the 2,383 Democratic magic number. Oh, and if any Democratic leader has pull to convince Sanders to be Sully Sullenberger, it might be Chuck Schumer, the likely Senate Democratic leader come 2017. Remember, Sanders will be returning to the U.S. Senate.

Clinton is now 92 delegates away from hitting magic number

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As for Hillary Clinton, her apparent win in Kentucky was by the narrowest of margins (less than 2,000 votes), despite pulling out all of the stops (extra campaigning, advertising dollars). She got the symbolic win she wanted to avoid being shut out in May’s contests, but it was more relief than euphoria. Yet in terms of the overall delegate race, last night’s results really didn’t change much: Sanders picked up 55 pledged delegates to Clinton’s 47 (Sanders +8), with three delegates outstanding in Kentucky and 11 in Oregon. Here’s the updated Democratic delegate math:

In pledged delegates, Clinton currently holds a lead of 274 delegates (was 282 before yesterday)

Clinton 1,764 (54%)

Sanders 1,490 (46%)

Clinton must win 33% of remaining pledged delegates to get a majority in pledged delegates (was 34%)

Sanders must win 67% of remaining pledged delegates to get a majority in pledged delegates (was 66%)

In overall delegates (pledged + super), Clinton holds an overall lead of 762 delegates (was 768 before yesterday)

Clinton must win 10% of remaining delegates to reach 2,383 magic number (was 13%)

Sanders must win 90% of remaining delegates to reach 2,383 magic number (was 87%)

Trump’s late start

Turning to the Republican race, Donald Trump last night reached a joint fundraising agreement with the Republican National Committee, allowing him to collect checks as large as $449,000 to benefit his campaign and party. But consider this: Hillary Clinton reached her own joint fundraising agreement with the DNC in August of 2015 -- so almost a year ago. And when you throw in the fact that Trump JUST hired a pollster and that there still isn’t a designated pro-Trump Super PAC, you see how late of a general-election start Trump is getting, all less than six months before Election Day 2016. As for Trump’s interview with Fox’s Megyn Kelly, well the Trump-Fox relationship has never been stronger; they’ve’ definitely patched things up.

Clinton narrowly leads Trump in New Hampshire, but they’re both down-ballot drags

Finally, a new WBUR poll finds Hillary Clinton barely leading Donald Trump in New Hampshire among likely voters, 44%-42%. In the competitive Senate race in the Granite State, it's Democrat Maggie Hassan 48%, GOP incumbent Kelly Ayotte 46%. And check this out from Politico: “While 33 percent said Ayotte's support for Trump makes them less likely to vote for her, 14 percent said it would make them more likely to back the Republican senator. (Another 53 percent said it would make no difference.) By comparison, 26 percent said Hassan's support for likely Democratic presidential nominee Hillary Clinton made them less likely to support Hassan, but only 8 percent said it made them more likely to back her. Sixty-five percent said it wouldn't make a difference.” Bottom line: Both Trump and Clinton are down-ballot drags here.

On the trail

Bernie Sanders campaigns in California.