“I’m going to hold a fundraiser right here, right now, across America,” Bernie Sanders told his crowd of supporters at his New Hampshire victory party on Tuesday night, before reading out the address of his campaign website. “Please help us raise the funds we need—whether it’s 10 bucks, 20 bucks, or 50 bucks. Help us raise the money we need to take the fight to Nevada, South Carolina, and the states on Super Tuesday.”

Sanders supporters watching at home were listening. According to his staff, Bernie raised roughly $6.5 million between when the New Hampshire polls closed and 8 p.m. the following day—roughly double his previous 24-hour record, which he set directly after his historically narrow defeat in the Iowa caucus at the start of the month. When you combine just those two days with the staggering $20 million that he says he raised in January alone, Bernie brought in at least $29.5 million in the first six weeks of 2016—nearly as much as he did in the final three months of 2015, when he raised a personal record $33.6 million.*

His opponent, of course, is no slouch in the fundraising department. Hillary Clinton outraised Sanders by roughly $40 million last year, bringing in a total of $116 million in 2015. She also has a personal fortune to fall back on if things ever get tough, as she did back in the 2008 cycle when she gave her campaign more than $13 million. And, of course, she has the additional advantage of her aligned super PAC, Priorities USA, which raised $41 million last year, as well as the support of other outside groups with millions to burn. Clinton’s in no danger of running out of resources.

Those top-line numbers, though, obscure Bernie’s biggest strength: his small donor base. His campaign reported receiving more than 2.5 million donations from more than 1 million individuals in 2015, numbers he reached faster than Barack Obama did during his first presidential campaign in 2008. Those are accomplishments Sanders can—and does—tout on the stump as proof of his campaign’s strength and staying power, while also providing him the desired contrast with the large-donor political status quo he’s promising to overturn. He’s harnessed the power of the attention grabbing “money bombs” that lesser candidates used a decade ago, and folded it more fully into his message. As his campaign materials never hesitate to point out, his political operation is paid for by Bernie, “not the billionaires.”

As important as his narrative, though, is his financial reality. Sanders’ small-donor network serves as a near-renewable resource that he can continue to tap until his fans either can’t afford to give any more or they reach their maximum contribution limit of $2,700, whichever comes first. His campaign can solicit small donations in good times (when he wins a primary) and bad (when Clinton attacks), and in between. Clinton doesn’t have that same luxury since a significantly higher percentage of her donors have already given all that they legally can. Consider: 72 percent of Sanders’ donations last year were for $200 or less, compared to only 16 percent of Clinton’s. When Hillary wants an infusion of cash, her staff needs to find new donors, either through online outreach or by holding traditional fundraisers, both of which take time and money. When Bernie wants to make a splash, he just needs to step on stage and ask his existing ones.

Read more of Slate’s coverage of the Democratic primary.

*Correction, Feb. 11, 2016: An earlier version of this post misstated the year that Sanders set his current quarterly fundraising record. It was the fourth quarter of 2015, not 2016.

