Sen. Bernie Sanders (I-Vt.) speaks at a campaign rally in Hartford, Conn., on Monday. (Mike Segar/Reuters)

A year ago this week, when Sen. Bernie Sanders (I-Vt.) announced that he was running for president, his campaign was widely dismissed as nothing more than a protest candidacy.

Over the past 12 months, Sanders has defied the expectations of many in the political and media establishment. He has proven that there is a vast constituency of voters who are hungry for the progressive ideas at the heart of his campaign. And he has pushed Democratic front-runner Hillary Clinton to take bolder positions. But now, as the delegate math for Sanders grows more daunting, some Clinton supporters and pundits are calling on him to drop out of the race. Sanders should ignore them.

Clinton is almost certain to be the Democratic nominee, but those demanding that Sanders drop out are once again underestimating what he can accomplish by staying in the race. By continuing through the final primaries in June, and entering the July convention with more delegates and primary victories than any true dark-horse candidate in modern history, Sanders still has an opportunity to both influence the direction of the party and increase its chances of victory in the general election.

The Democratic convention can and should be more than a coronation. It’s where the party officially decides on its rules and its national platform. With the rules and platform committees already stacked with Clinton supporters, it will be important to make sure the issues that Sanders has injected into the debate are fairly reflected in the party’s agenda. If he drops out of the race now, Sanders and, by extension, his supporters will lose significant leverage over the policies that define our politics for the next generation. But if he continues to fight, he can ensure that the Democratic platform includes strong representation of the ideas driving his campaign.

Before endorsing Clinton, for example, Sanders could force platform debates and move the party toward more progressive stances on tuition-free higher education, the minimum wage, corporate trade deals, money in politics and foreign policy. He also could call for new rules to make future primaries more transparent and democratic, such as reducing the role of unelected superdelegates.

This is not to suggest that Sanders should be gearing up for the kind of bitter floor fight that some Republicans are plotting to stop Donald Trump. Rather, a better comparison is the Democratic primary in 1988. That year, insurgent candidate Jesse Jackson campaigned well into the summer before giving his support to Michael Dukakis at the convention, where he also secured floor debates on key issues and a prime-time speaking slot. While some complained that he was dividing the party, Jackson rightly contended that he was promoting reconciliation at the end of a hard-fought campaign. “We grow through debate and deliberation,” he said. “We can have unity without uniformity.”

But until that unity has been achieved, Clinton could actually suffer as a consequence of Sanders conceding too early. After a nomination contest that has been ugly at times, albeit much less divisive than 2008, some voters may be more reluctant to back Clinton if they believe that she prematurely forced Sanders out of the race. On the other hand, if they feel like their voices have been heard, and if they stay engaged as a result, Sanders supporters have the power to help propel Clinton and other Democratic candidates to victory in November.

Indeed, as long as both candidates take the high road between now and the convention, Sanders’s presence could strengthen Democrats’ chances of holding onto the White House and regaining control of Congress. His campaign has already given the party a much-needed boost: Seven in 10 Democratic voters in last week’s New York primary, according to exit polls, said the nomination fight has energized the party as opposed to dividing it. And while Sanders has indicated that the extent of his potential support for Clinton will depend on her platform in the general election, he has begun using his considerable influence to help elect more progressive women candidates to the House.

In the end, history will not judge the Sanders campaign by the number of votes he won, though he has won many, but rather by how it has shaped this remarkable moment and continues to shape future debates. As Sanders said recently, “When people respond by the millions to your message, then that message is now mainstream. That changes political reality.” Yet, while Sanders has already changed our political reality, he can still aim higher — if not toward the Oval Office, then toward a Democratic Party that is more progressive and therefore more likely to continue the political revolution that he started.

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