As the early primary contests in Iowa and New Hampshire near, Democrats unhappy with their party’s establishment have much to celebrate. Over the past seven months, the presidential campaign of Vermont Sen. Bernie Sanders, a self-described socialist who caucuses with the Democrats, has produced a serious national debate about democratic socialism and the battle to confront inequality in the United States. Sanders has already accomplished far more than most professional commentators had expected, with tens of thousands of people turning out to see him speak. The senator may not have a Super PAC, but his campaign raised $41.5 million as of the last Federal Election Committee filing in October, almost entirely from small donors, becoming the first campaign to reach two million donors this election cycle. Millennials have been donating money to his campaign at an impressive rate. Sanders may yet surprise the political class with strong returns in the opening caucuses and primaries. But sooner or later, all good things must come to an end. Realistically, Sanders’ chances of defeating the Democratic frontrunner, former Secretary of State Hillary Clinton, are very small. Even if he has performed better than anyone initially gave him credit for, he’s still a long shot, having never led Clinton nationally among Democrats. Moreover, Sanders has vowed that he won’t run as an independent if he loses the primary, for fear of dividing the liberal vote and ensuring a Republican victory. This means that he will likely endorse Clinton, whether or not his supporters approve. It’s not too soon for those supporters to start asking what’s next.

Failures at movement building

Even if Sanders were to pull off a miracle and win the White House, he would need a strong progressive movement to get anything done. “This campaign is not about electing Bernie Sanders for president,” the candidate tweeted last August. “It is about creating a grassroots political movement in this country.” Progressive presidential candidates have often failed to build organizational infrastructure to continue the fight. In 2008, Barack Obama created a remarkable field campaign, Obama For America, which enlisted the largest number of volunteers ever amassed by an American presidential candidate. After his victory, he suggested that the group — which was rebranded Organizing For America (OFA) — would continue as a grassroots advocacy operation. Obama’s camp made much of their plans for OFA and its 13 million-person email list, 4 million donors and 2.5 million activists. “This would be the greatest political organization ever put together, if it works,” said Ed Rollins, a longtime Republican campaign strategist and advisor to President Ronald Reagan, in an interview with Rolling Stone. “No one’s ever had these kinds of resources.” Sadly, many activists energized by the Obama campaign soon found themselves disillusioned with OFA. As the new administration formed, the White House scrapped plans for an independent organizing operation that would put pressure on all politicians. Rather, it wanted loyalists willing to rally in support of the administration’s policy proposals. Ultimately, OFA became a wing of the Democratic National Committee, and its once-mighty grassroots swagger faded into history.

Sanders offers a unique opportunity for progressives to generate fresh energy and draw in people who are otherwise disengaged.

Obama’s inability to channel the energy of his first presidential campaign into a lasting movement is not unique. As Harold Meyerson argued in The Washington Post, “Robert LaFollette’s 1924 independent campaign failed to create an ongoing institution.” Likewise, “the Rainbow Coalition that emerged from Jesse Jackson’s campaigns in the ’80s never had the autonomy it needed to move beyond Jackson’s narrow post-campaign agendas.” But where Democrats have struggled to harness grassroots movements, Republicans have enjoyed more success.

Learning from Goldwater