Beto O’Rourke reported raising more than $6.1 million during the first 24 hours of his presidential campaign, a record-setting haul that narrowly tops the amount announced by Sen. Bernie Sanders and dwarfs everyone else in the 2020 field.

O’Rourke was a fundraising juggernaut during his U.S. Senate race in Texas last year, but there were significant questions about whether that would translate to a national campaign where he was running against fellow Democrats, not Republican Sen. Ted Cruz.

The answer appears to be yes.

O’Rourke’s campaign said he raised $6,136,763 from donations that came from all 50 states, D.C., and every U.S. territory.

“In just 24 hours, Americans across this country came together to prove that it is possible to run a true grassroots campaign for president — a campaign by all of us for all of us that answers not to the PACs, corporations, and special interests but to the people,” O’Rourke said in a statement.

In his first day as a candidate, Sanders (I-Vt.) reported raising $5.925 million from 223,000 donors, which brought his average contribution to $27.

O’Rourke’s campaign would not release the total number of donors or the amount raised any subsequent days.

Sen. Kamala D. Harris (D-Calif.) reported raising $1.5 million from 38,000 donors in the 24 hours after she announced her campaign. Sen. Elizabeth Warren (D-Mass.) did not announce how much she raised, but on her first day, she pulled in at least $300,000 from 8,000 donors, according to fundraising figures reported by ActBlue, an online fundraising organization used by Warren and other Democrats.

Several Democratic campaigns — those of Sen. Amy Klobuchar (Minn.), Gov. Jay Inslee (Wash.) and former governor John Hickenlooper (Colo.) — said they raised about $1 million over 48 hours.

There is no way to confirm the figures the campaigns are releasing until they file reports with the Federal Election Commission in several more weeks.

With at least 15 candidates in the race, fundraising is a crucial barometer for demonstrating who can attract broad enough support to sustain a campaign. It is also a metric used by the Democratic National Committee to qualify for the debates, which are scheduled to begin in June.

But the presence of so many candidates could complicate fundraising, because some of the candidates came into the race with overlapping lists of donors.

The figures so far establish O’Rourke and Sanders as the two most prodigious fundraisers out of the gate and could set up a clash between the two. Sanders is more liberal than O’Rourke and has staked his campaign on specific policy proposals that O’Rourke so far lacks.

Sanders’ supporters at times prodded O’Rourke during his Iowa trip last week, asking pointed questions about his positions on health care or his past alignment with more moderate stances.

O’Rourke eschewed the socialist label that Sanders embraces and said he considers himself a capitalist. When a CNN reporter asked Sanders about O’Rourke’s entry into the race, the senator shrugged. “Free country, anybody can run,” he said.

During his senate campaign, O’Rourke raised more than $80 million, the most collected for a single such race, and built a national list of supporters that he has sought to tap since his presidential announcement Thursday morning.

In the hours after he announced, several emails and text messages were blasted out to his supporters, urging them to donate. At one point during a first day spent campaigning in Iowa, he stopped at a gas station, broadcasting on Facebook Live that it had cost $28.53 to fill up the Dodge Caravan he was driving and urging people to donate to help fuel his road trip.

Several of his rivals also made fundraising appeals tied to him entering the race.

Since Thursday, O’Rourke had declined to release his fundraising figures — “I choose not to,” he said several times — which triggered speculation that he wasn’t faring as well as he and his campaign had hoped.

O’Rourke has pledged not to take donations from lobbyists or from corporate political action committees. He has not gone as far as Warren, who has said she will not hold any high-dollar fundraisers.

“I’m not planning to do large-dollar fundraisers,” O’Rourke told reporters in Dubuque, Iowa, on Saturday night.

But he left open the possibility that he could hold such fundraisers in the future, answering “no” when asked if he was, like Warren, ruling them out completely.

“Right now, we’re ruling out taking any PAC money or any lobbyist money ever,” he said. “I have no large-dollar fundraisers planned and I don’t plan to do them.”

O’Rourke has yet to announce his campaign staff, including who will serve as his campaign manager.

He said in Dubuque that he would support his campaign workers unionizing, as Sanders’ campaign has announced it would do.

“If that’s what the employees of this campaign want to do, I’m very supportive of that,” he said. “I hope that we will be paying the most competitive wages, providing the most competitive health-care and child-care benefits to our employees who will comprise the heart of this campaign.”

O’Rourke was scheduled to campaign in Michigan and Ohio on Monday.