Bernie Sanders can’t win. If it’s not a fact just yet, it’s at least quickly hardening into one. Before the Tuesday slate of primaries, he needed hundreds of delegates to keep pace with Hillary Clinton and hundreds more to overtake her substantial lead, and he needed to accomplish the feat in environments that have vexed him from the start: large, diverse primary states. New York was one such shot, and he missed it. Tuesday’s big prizes—Pennsylvania, Maryland, and Connecticut—offered another opportunity, and he missed that one, too. Clinton has lapped Sanders, and short a significant boost (or a blue shell) he will remain far, far behind.

But Sanders isn’t your typical losing candidate. By every other metric, he’s still in the game. Sanders out-raised Clinton each month of this year. He outspent her, too, putting up ads at a 2-to–1 ratio in the New York primary. And that machine hasn’t slowed down. Not only did Sanders outspend Clinton by the same ratio in almost every state that voted on Tuesday, but he’ll likely beat Clinton in fundraising for April as well, surpassing her total amount after starting the race at a huge cash disadvantage.

Even if Sanders is mainly capitalizing on existing trends and technologies, his swelling coffers are a remarkable and a dramatic change from the usual dynamic wherein challengers are more or less finished after Super Tuesday, and the ones who have the will to continue lack the money to do so. Sanders, by contrast, has both the cash and the will to press on. And he should. Far from packing up or giving in to any pressure to quit, Sanders should fight through the remaining primaries, and take his campaign to the Democratic convention in Philadelphia.

Team Sanders says that’s the plan. “We’re going to go to the convention,” said campaign manager Jeff Weaver in an interview with MSNBC’s Steve Kornacki. “It is extremely unlikely either candidate will have the requisite number of pledged delegates to reach the magic number of 2,383 needed for the nomination. So it’s going to be an election determined by the superdelegates,” he said. But this isn’t a plan to take the campaign to the convention as much as it’s a plan to win at the convention by wangling superdelegates—Democratic lawmakers and other officials—over to their camp. It’s a bad plan. Barring a catastrophe, those lawmakers and elites will stick with Clinton. Sanders won’t gain from trying to flip superdelegates to win from behind; more likely, he’ll only alienate people.

Team Sanders needs to give up on winning the nomination. That battle is over. But Sanders still has an unprecedented opportunity to leave a stamp on the Democratic Party. By fighting in remaining primaries and caucuses—by raising huge sums and drawing massive crowds—Sanders can show the extent to which his message resonates with millions of Democrats, including the young voters and activists poised to lead the party in the future. He shows, in other words, the extent to which the party belongs to his ideas, even if it doesn’t belong to him—a fact he can underscore with new polls showing a large leftward swing among millennial voters, and a similar swing among Democrats writ large.

It’s also an opportunity to bring his support to down-ballot candidates. For the Sanders campaign to make lasting change as a Sanders movement, it needs to seed like-minded politicians throughout every office from the Senate to the school board. A presidential campaign of the size and scale attained by Sanders is a perfect opportunity to build a counterestablishment movement within the Democratic Party. Liberal groups like Democracy for America and the Progressive Campaign Change Committee have endorsed candidates vying for seats in upcoming states like California and New Jersey. Team Sanders can showcase them and even encourage donations to their campaigns, providing a tangible assist and building the kinds of political ties that last. And if Sanders can help elect these progressive Democrats, he has allies for when he returns to the Senate.

All of this, together, will build leverage for the convention, so that Sanders can shape the Democratic Party platform and win real concessions from the Clinton campaign, on everything from the shape and design of future primaries to actual policies.

But if Sanders wants to maximize that leverage, he needs to retool his message away from Hillary Clinton. As it stands, she’s still in his crosshairs. “This campaign is about taking on the entire establishment. The Democratic establishment, the financial establishment, and in Clinton’s campaign, the most powerful political organization in the United States of America,” said Sanders during a town hall interview with MSNBC’s Chris Hayes. Yes, Sanders plans to work against the Republican nominee for president, whoever he is. But in terms of his relationship with the Democratic Party, direct attacks on the standard-bearer—already bruised by a lengthy primary and persistent questions of trustworthiness—don’t help. Indeed, for rank-and-file Democrats, they’re ammunition for the eventual Republican assault.

It may seem like useless theater to massage the feelings of the winning side, but it’s not. There’s strategy at work. Any negotiations between Team Clinton and Team Sanders will be hard work, as the former tries to protect its turf and the latter tries to press its advantage. Sanders will come to the convention with strength, but as the loser, he’ll still be working from a position of weakness, not strength. Continued attacks on Clinton won’t change that. Instead, they’ll create enmity, and enmity is bad for negotiations. People dig in when they dislike each other. They don’t want to concede. Beyond that, Sanders’ leverage doesn’t come from his ability to criticize Hillary Clinton—anyone can do that; it comes from his ability to raise money and build enthusiasm. To paraphrase Teddy Roosevelt, he has a big stick in the form of his primary success. Now he needs to speak a little softly.

To win the most possible leverage, Sanders will have to return to his old rhetoric of ideas. And after years of official distance from the party, he will have to act like a loyal Democrat. This will be an uneasy posture for a lifelong gadfly. But the payoff—a Democratic Party bearing the Mark of the Bernie, with a full-on Sanders faction exerting pressure from the left—would be worth the price. That’s how you create a lasting legacy in American politics.

Read more Slate coverage of the 2016 Democratic primary.