Sen. Bernie Sanders (I-Vt.) rejoined the campaign trail in Tuesday night’s debate for the first time since his heart attack this month. During his time convalescing, conventional wisdom has effectively ruled him out as a potential nominee and concluded that he will have to drop out if, as polls suggest, he fails to win any of the four early contests. His huge third-quarter fundraising haul — combined with the Democratic delegate rules — show why this wisdom might be wrong.

Sanders’s $25.3 million in new contributions last quarter shows that his backers’ enthusiasm has not dimmed. He continues to rake in more money from his committed band of 1 million small-donor loyalists despite slipping in national polls. Sen. Elizabeth Warren (D-Mass.) may have surged in support among Democratic progressives at Sanders’s expense, but that has not yet impacted his appeal to his base.

This enthusiasm gives Sanders what other candidates whose support flags don’t: staying power. Rather than spend time and effort chasing big-dollar donors whose support is often contingent on good poll numbers, Sanders can actively campaign secure in the knowledge that his army will keep sending political ammo. It also contributes to good press, as the media won’t be writing about a campaign on death watch as fundraising numbers disappoint.

This wouldn’t be the case for normal candidates who fail to win early. Sanders trails in all of the four early contests of Iowa, New Hampshire, Nevada and South Carolina. If he does lose all four, a normal candidate would see the writing on the wall and quit. But Sanders is not a normal candidate, and Democratic Party delegate rules would give him immense power if he stays in the race despite his defeats.

The Democrats’ proportional allocation of delegates is key to understanding why Sanders could stay in the race despite finishing third. Unlike Republicans, who give states great leeway to set their own rules about allocating delegates, Democrats have a national, one-size-fits-all approach. Every state must give delegates according to that person’s share of the popular vote if he or she gets 15 percent or more. That means Sanders will pick up delegate votes as long as he hits that threshold — and polls suggest he will in most states.

That sets up the strong chance that Sanders would be the kingmaker at next summer’s Democratic convention. Suppose the other two current front-runners, Warren and former vice president Joe Biden, keep finishing first and second. If Sanders nevertheless stays in the race and picks up 15 to 20 percent of the delegates in each state, neither Biden nor Warren would have enough pledged delegates to win the nomination. Democratic Party officials who have automatic delegate posts — the “superdelegates” — cannot vote on the convention’s first ballot, according to rules changes forced on the Democratic National Committee by Sanders backers. That means that Sanders would be in a position to choose the next nominee by cutting a deal with one of the other two.

Sanders surely wants to be president, but he wants to push the United States leftward just as much. He is proud to be called a democratic socialist, and even today he has not joined the party whose nomination he seeks. Being the Democratic Party’s power broker gives him immense power to accomplish his ideological goal. As long as he can stay in the race, there’s no reason for him to drop out and throw away his last chance to fulfill his lifelong dream.

That’s where his fundraising prowess comes into play. Most losing candidates see their money dry up quickly as the defeats pile up. They don’t drop out because they want to go; they drop out because they cannot afford to continue.

But Sanders’s backers don’t care. They’re in it for the revolution, not the game. They kept sending Sanders money when he was losing to Hillary Clinton; they are sending money to him now even when he’s sliding; and they will likely keep sending money to him even if he falters. They will especially want to give him money if he wisely transforms his campaign into an ideological crusade with explicit calls to make him and his cause the kingmaker.

Sanders has defied conventional wisdom before, shocking the experts with his strong 2016 showing. Assuming his health holds up, don’t be surprised if he shocks conventional wisdom again and ultimately becomes the most important Democrat in the country next July.

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