So he finally did it. Bernie Sanders endorsed Hillary Clinton at 11:29 a.m. Tuesday — about four weeks, three days, two hours, and 30-odd minutes later than Clinton wanted it to be, but which history will likely record came in plenty of time to help Clinton win in November.

“I have come here to make it as clear as possible as to why I am endorsing Hillary Clinton and why she must become our next president,” Sanders thundered, about a quarter of the way into his remarks that lasted about half an hour. He went on to make a strong and plausible case, from his perspective, praising Clinton and bashing Donald Trump on everything from inequality to wages to climate change to civil rights to the Supreme Court and just about everything else under the sun.

As he spoke, Clinton stood off to the side, behind his right shoulder, doing that Hillary thing of nodding theatrically at roughly every other sentence, applauding occasionally. There were a few moments when she got that “all right, man, get on with it” look on her face. Bernie, I thought, was trying to be about as nice as Bernie can be. He might have chosen to twist the knife a couple of times, just a little, but he didn’t. Notable example: When he went on his riff about the minimum wage, he shocked me by not specifically mentioning the $15 figure, which he has pushed and Clinton has shown ambivalence on. He just settled on the vaguer “a living wage”—especially surprising considering that his people got the $15 figure into the platform.

More shockingly than that, he mentioned very early on that “Secretary Clinton goes into the convention with 389 more pledged delegates than we have.” Sanders spent the last two or even three months of the campaign carrying on about the superdelegates, misleading his supporters into thinking that Clinton was winning only because of them, while refusing to acknowledge that she was winning more pledged delegates and that it was basically mathematically impossible for him to catch her on pledged delegates from March 15 onward. So his mere use of the phrase was, to the cognoscenti, a major emotional concession.

I’d have liked to hear him speak more directly on two points. First, I’d like to have heard him say directly to the Bernie-or-bust set that they have to go out and vote for her, and why. And second, I’d like to have heard him say directly to those supporters of his who are thinking of moving to Trump that they just can’t do that, and why. But all in good time I suppose.

Sanders gave every indication that he’s going to be hitting the trail heavily for Clinton. At four or five different points, he said something like “I am going to do everything I can to make” a Clinton victory happen. And she repeatedly said things like “Senator Sanders and I are going to make sure” Americans know the stakes, suggesting that she anticipates if not more joint appearances, then at least Bernie as a regular presence out there in her behalf.

It’s not yet clear what Sanders’s convention role will be. But based on what we saw in New Hampshire, the hatchet is pretty much buried. They didn’t look like they love each other. When he finished his remarks and she came to the podium to deliver hers, they shook hands and smiled but they didn’t really quite look directly at each other. It was that kind of awkward, non-eye-contact thing.

But they don’t have to be best buddies. They’re in a relationship now of mutually beneficial symbiosis. Clinton knows that the happier she manages to keep Bernie, the more likely she is to win in November.

Sanders knows that his best shot at taking what he’s created and turning it into tangible gains rests on a Clinton win and Democratic recapture of the Senate, where he would chair the HELP Committee, which oversees labor, education, and health. A Trump win means humiliation for Clinton, and for Sanders, it means that the Democrats in Congress would just spend the next four years playing defense, which in turn would mean the likely dissolution of his movement, especially given his age. So like the proverbial scorpion and frog, they need each other to get across the river, no stinging allowed!

First, let’s see if she gets a bounce out of this in the next few days. There’s a lot of campaign news about to break—namely two vice-presidential announcements. If this morning’s event manages to get a couple days’ attention, it should get her two to four points, I’d think.

Then, over time, Sanders can make a huge difference for her if he decides that’s what he wants to do. If she’d never done that stupid email thing, she’d be 12 to 15 points ahead, and she wouldn’t need him. But she did it, and she isn’t, and she does. She holds leads in virtually all the swing states, but they’re narrow leads. Sanders can make a difference in Pennsylvania, Michigan, New Hampshire and maybe Iowa and Ohio.

The only question that hangs over this feel-good party is whether Clinton went a little too far left in her remarks. Except for some balancing-out praise for cops, she sounded a lot like Bernie. Senator Jeff Merkley, Sanders’s only endorser among Democratic Senators, gushed on MSNBC about how progressive Hillary sounded, using new anti-TPP rhetoric, for example. And RNC chair Reince Priebus picked up on this in his statement, wryly noting this “hollow display of left-wing solidarity.”

Against John Kasich, all this may have ended up a liability. But against Trump? Well, time will tell. In the meantime, everybody sing: