Sanders sees himself as leading a movement, not just engaged in a political campaign. At this point, he is running on the passionate commitment of his supporters, and his belief that to drop out now would be to betray their faith in him. At least in part, what made him run in the first place is the belief that the cause is bigger than him. Moreover, by staying in the race, he has greater leverage over the platform, and that may be an important consideration for him, if not for his supporters.

Sanders knows that by staying in the race, he can influence the platform, even if he fails to win another primary contest. But he has a real chance of winning more contests. Indiana, which he won narrowly by about three points—but with no one seriously predicting a Sanders win—was a real boost to the Sanders campaign. He won West Virginia by about 15 points, a state Clinton won easily over Barack Obama in 2008. Sanders was clearly helped by Clinton’s self-inflicted wound with her comments (which were actually taken out of context) about the demise of the coal industry (and which were used by Trump but not by Sanders, who is a more committed climate activist than Clinton). He has a good chance at winning Kentucky next Tuesday, and he may even have a decent shot at California on June 7. None of this will put him within reach of the nomination, though, given a nomination system with so much weight placed on the super delegates, who are almost all for Clinton.

Even with her strong super delegate support, though, Clinton must have nightmares about 2008, wondering if the same dynamic will play itself out this year. Logically, that shouldn’t happen. Clinton is far ahead of Sanders in the total delegate count, and is only about 150 delegates away from locking up the necessary 2,383 delegates and being declared the presumptive nominee. But a lot of loyal Democratic voters just do not like her, or are about as tepid in their support of her as Mike Pence’s limp endorsement of Ted Cruz just before the Indiana primary.

Sanders can keep racking up wins, keep calling attention to Clinton’s weakness among fellow Democrats, and hope for a black swan event. But without that black swan, there is no viable path to victory. That black swan, of course, goes by the name “FBI.” While an indictment of Clinton in the email controversy is highly unlikely (since any indictment by a grand jury would require approval at the highest levels of the Justice Department and the president himself), anything that tarnishes her reputation, or that suggests recklessness in an official capacity, could be politically debilitating—if not disastrous. Under those circumstances, however unlikely any of them might be, why should Sanders not hang in and wait it out? If Clinton’s poll numbers really did start to go south, the Convention just might turn to Sanders. If the shoe was on the other foot, does anyone doubt that Clinton certainly would hang in there?

One thing Sanders could do to generate some additional interest in the closing weeks of the campaign is to pull a Ted Cruz (although hopefully with greater effect) and announce his VP pick. One name that has been floated, and that would be a great catch if she would accept, is Elizabeth Warren, U.S. senator from Massachusetts, progressive populist, and bete noir of Wall Street. Another possibility—which would be electrifying—is the young congresswoman from Hawaii, Tulsi Gabbard, who broke with the DNC and Debbie Wasserman-Schultz when she announced her support for Sanders months ago.

Clinton would dearly love to wrap it up so she can begin focusing exclusively on the general election, but she just can’t seem to close the deal. But from Sanders’ standpoint, there is absolutely no reason to quit.

Dr. Euel Elliott is a professor of public policy and political economy and the associate dean in the School of Economic, Political and Policy Sciences at the University of Texas at Dallas. He is the author of the soon-to-be published books,Paths not Taken: The What Ifs of American History from theWar for Independence to the Bush-Gore Election andAdventures of Maia Neeri of the 24th Century.