On Wednesday, rumors flew that Sen. Bernie Sanders was dropping out of the presidential race. Those reports turned out to be in error, but I wish they had been true.

Former Vice President Joe Biden didn't just defeat the progressive senator from Vermont in Tuesday's primaries. He crushed him. As of Wednesday morning, with almost 90 percent of votes counted, Biden was ahead of Sanders by 12 points in Arizona. In Illinois, he won by 23 points, and in Florida he won by a whopping, embarrassing 39 points. NBC News' count now puts Biden more than 300 delegates ahead of Sanders. The Economist's poll average has Biden 28 points ahead of Sanders nationally.

Sanders has, in short, no path to the Democratic presidential nomination. He's lost.

Sanders has, in short, no realistic path to the Democratic presidential nomination. He's lost, and it's time he drops out for the sake of the progressive movement he's championed. I'm not a Biden fan, but by continuing to campaign, Sanders only reduces his influence at a critical juncture. His best bet to push the party left now is to end the race, endorse Biden and start focusing on the general election against President Donald Trump.

Some Sanders critics have argued that his continued campaign puts people's lives at risk from the coronavirus. This argument is unfair and neatly elides the existence of local elections. Even if the presidential campaign ends, most states still need to figure out safe ways to hold primaries (probably through expanding vote by mail).

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The real risk from Sanders' continued campaign is not to public health but to his own standing and influence. In 2016, Sanders continued his campaign long after he had much chance of defeating Hillary Clinton. But while he couldn't win the primary, he continued to rack up impressive victories in many caucus states and a huge upset win in Michigan's primary. He was able to demonstrate that progressive ideas and candidates had a strong appeal, which put him in a good position to push the party platform left at the convention.

This year, though, Sanders lost Michigan by double digits, and he has lost in former strongholds like Washington state. When he goes out week after week and gets badly beaten, he doesn't make the progressive movement look strong. He makes it look anemic and ineffectual.

Part of Sanders' problem is that the Democratic electorate is very focused on Donald Trump. After a huge, diverse field shrank quickly this spring, there is little appetite for a long, drawn-out primary with Democrats sniping at one another. After Biden won South Carolina, the Democratic Party — elected officials and voters alike — coalesced around him immediately because they wanted the primary process to be over.

By dropping out, though, Sanders can strengthen his place in the party and advance progressive goals. Biden has already shown himself open to embracing some of the left's policies. He's recently promised to adopt Sen. Elizabeth Warren's important bankruptcy reform plan and a Sanders proposal from 2017 to offer free public college tuition to all families with incomes under $125,000. Sanders has since expanded his plan to include free college for all, which Biden doesn't support. But it's still hopeful that Biden has tried to meet Sanders halfway.

Sanders might be able to get further concessions, as well, either as part of a deal to drop out or at a convention where he's seen as a strong ally of the nominee. "Medicare for All" is probably out of reach, unfortunately. But Sanders might be able to get Biden to commit to embracing free college for all or eliminating some part of college debt or restoring voting rights for those who have committed felonies. Sanders has a range of exciting, progressive ideas that would materially help Americans in need and make the country more just and more equitable. If he can use his current leverage to get Biden to embrace any of them, it's a win.

Just as important as policy wins is the future role of the left within the Democratic Party. Sanders ran an ambivalent campaign, in which he and campaign surrogates sometimes positioned him as an outsider who intended a hostile takeover of the Democratic establishment. Whether true or not, this hurt him with an electorate and a party that wants to present a united front against Trump. It made it look like the left wasn't part of the team or wasn't sufficiently focused on victory in November.

But Sanders can change that perception now. If he endorses Biden, works hard for his re-election and brings on board his own surrogates and voters in the fight against Republicans, he can demonstrate that progressives are not a barrier to defeating Trump but a powerful and motivated constituency that can help deliver victories. That's a legacy on which future progressive candidates will be able to build, both in down-ballot races and in future presidential contests.

Sanders has done a huge amount to mainstream progressive ideas and progressive movements. His two campaigns have unleashed unprecedented electoral energy and enthusiasm on the left. Even though he's lost, he can do more. Losing the primary is painful. But Sanders' campaign slogan is "Not me. Us." His stated goal was not a personal victory but a better world for everyone. And by dropping out, he can help the left win next time.

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