Joseph Robinette Biden won a presidential primary tonight, the first of his long career in politics. He shocked the national punditocracy with a win that went far beyond all expectations. He delivered the speech of his career, and for the first time in a long time had a happy warrior aspect that was a very different Joe Biden than we’ve seen in the past, gloomy weeks. Biden’s win reset the race, and means that there are a lot of hugely consequential decisions coming for almost everyone even tangentially involved.

The biggest decisions are in the hands of two men: Barack Obama and Mike Bloomberg.

Obama is the most important player in this equation.

He almost certainly will resist this idea, but Obama should play a leadership role in a party bereft of leaders by endorsing Joe Biden before Super Tuesday. Tomorrow would be good.

Here’s the simple, 60-second script that would melt down every social media platform in the world:

I’m Barack Obama. For eight years, Joe Biden was at my side in the most important fights of our time. He shares my vision for a nation that is more fair, more caring, and that honors our values and aspirations. He’s led on civil rights, health care, education, and helped make our country safer and more prosperous.

This race is too important for me to sit on the sidelines. The only thing that matters this fall is that we take back the White House from Donald Trump and retake the Senate, and the only man who can beat him is my friend Joe.

Joe is the right man to lead this fight, and this nation, and I am proud to offer him my wholehearted endorsement and support.

He’ll resist this idea, of course, because the Obama brand is one of laid-back, technocratic froideur. Obama is not a stupid man, and his hints about the disconnect between Bernie and general election voters show that he understands the risks for his party.

Obama can transform this race in a hot second. The question is if he will put his mouth where his heart is, man up and say out loud what he’s been whispering for months about how nominating Sanders helps re-elect Trump. It’s now or never.

Charles de Gaulle once said the nuclear forces didn’t need to destroy the Russians, but to tear off an arm or a leg. That may be the same place Mike Bloomberg finds himself in this race. Bloomberg may not be able to win this race, but he’s already changed it. He may not be able to capture the nomination and be the candidate to face Trump, but his firepower could help keep the pressure on Trump and the most powerful weapon Trump has in his portfolio—Democratic presidential candidate Bernie Sanders.

I’ve encouraged Mike elsewhere to nuke Bernie into a glowing puddle of radioactive slag, because if Bloomberg’s desire is to defeat Trump, he has to understand the risk Sanders poses in a general election. Bloomberg’s pet issues—climate change and gun control spring to mind—have a snowball’s chance in hell with Donald Trump’s second term, a Senate more firmly in GOP hands, and (in the worst case) a House back in Republican control. Bloomberg has promised to keep his massive infrastructure in place for the general election, no matter how the primary turns out, and the Democratic party desperately needs it. He can be a kingmaker and party-maker all at once.

The power of this night for Biden also leads to a lot of other questions and decisions for the rest of the field.

Biden beat Sanders like a rented mule. The exit polls told the tale; it was a crushing defeat across almost every demographic group, with three in five black voters overall choosing Joe. Thirty-five percent of black voters thought negatively about Sanders, versus 11 percent for Biden. Even young voters—ostensibly the core of Sander’s support—split their vote.

The idea that Bernie Sanders has an alchemical formula for turning out progressive voters and “expanding the electorate” collided with the reality of South Carolina, and Biden. The media had taken those assumptions as given, and now the cracks in Bernie’s electoral case will get a hard examination. Woke Twitter may be all-in for Sanders, but Woke Twitter gets exactly zero delegates.

Now comes the hard part for Biden. As James Carville remarked tonight, “There’s a whole lot of football left.”

But there’s also not much time on the clock with Super Tuesday looming, and Biden's campaign in desperate need of a financial jumpstart. The Super Tuesday results in states that have a similar minority composition to South Carolina should help Biden continue to rack up delegates, but California—sans an Obama endorsement that resets the game—is going to do what California tends to do and follow its impulses rather than its brain and deliver Bernie a big hit of delegates.

Over the next 72 hours, Pete Buttigieg and Amy Klobuchar will, barring some shocking change in the political trajectories of their campaigns, have to pull the ejection handle. They did well for themselves, but the game is done.

Pete Buttigieg has established himself as a compelling, smart candidate and I’m confident we haven’t heard the last of him, but right now he’s bogarting 8-10 percent of the “moderate lane” Biden will need to grab.

I’ve had a soft spot for the scrappy, slightly awkward Amy Klobuchar since the beginning, partly because she’s so go-darn Upper Midwest (you know, a place Democrats might want to try to win in 2020 after Trump’s 2016 lockpicking) and if she’s not on the VP shortlist, whoever wins the nomination is a damn fool. She too has a handful of delegates that Biden needs, and I suspect that he’ll need them all.

Both Buttigieg and Klobuchar are young enough, and will leave with enough cash still in the bank to keep their political operations in place for future efforts. They’ll have to answer the delegate and endorsement questions that face everyone who leaves the race and sooner than later, and if they want to help stop Bernie, sooner is better.

Tom Steyer’s financial bonfire of billionaire vanity is over now. It was a midlife crisis disguised as a campaign.

Elizabeth Warren is fading for a reason; just as Republicans failed to attack the frontrunner while Trump consumed them like an umber Cronus, so has Warren spent her time attacking Bloomberg while it’s Sanders who owned her base. As someone who believes that Bernie is Trump’s re-election insurance policy (a position shared by every single Republican consultant working for Trump), I want Warren to stay in the race until the last dog dies to keep Sanders’ delegate count down, but that’s just me.

South Carolina changed the game tonight. Now, we’ll see if the players understand just how important the right decisions in the coming days will be to their chances this fall against Donald Trump.