Joseph R. Biden Jr.’s presidential campaign announced Friday that it had raised $6.3 million in its opening 24 hours, surpassing the first-day totals of his rivals and easing concerns among some supporters over whether he would be able to compete financially in the Democratic primary.
Mr. Biden’s team had viewed his early fund-raising as an important metric by which his nascent candidacy would be measured. His campaign sent multiple emails asking for donations on Thursday, his first day in the race, and he attended a high-dollar fund-raiser in the evening.
On Friday, the campaign celebrated its total in a note to supporters, calling it “AMAZING news.”
Mr. Biden’s campaign said 96,926 people had contributed in the first day, and that 65,000 of the donations were from people who were not previously on his email list of supporters.
The campaign said 97 percent of online donations were below $200, but it declined to disclose the share of overall contributions that were below that threshold. The average given per donor was about $65, higher than the first-day averages reported by some rivals.
Mr. Biden has been perched at or near the top of most polls of the sprawling Democratic field. Still, he and his advisers spent recent days privately urging major donors about the importance of his financial showing in the first hours and days of the contest.
They pointed to key benchmarks such as the $6.1 million first-day haul for former Representative Beto O’Rourke of Texas, and the $5.9 million collected in 24 hours by Senator Bernie Sanders of Vermont. (Mr. O’Rourke’s total was inflated by $300,000 in general election funds that cannot be spent in the primary; Mr. Sanders and Mr. Biden are not collecting such funds.)
[Read more: Mr. Biden entered the campaign with $0.]
Mr. Biden held a conference call on Wednesday, the eve of his announcement, to rally and consolidate support from potential top contributors.
His haul was impressive, especially compared with the last time he ran for president. In all of 2007, Mr. Biden raised $8.2 million from individual donors.
Bernard L. Schwartz, an investor and Democratic donor, said he saw Mr. Biden as the party’s best chance to defeat President Trump, and was pleased Mr. Biden jumped in “with both feet.”
“He’s raised a lot of money the first day,” said Mr. Schwartz, who donated the maximum $2,800 and was on Wednesday’s conference call. “But the first day is only the first day.”
The bigger question for Mr. Biden was how he would fare among donors making small contributions online, who have become the new currency of Democratic politics. Unlike Mr. Sanders, who ran for president in 2016, and Mr. O’Rourke, who set fund-raising records as a Senate candidate in 2018, Mr. Biden did not enter the race with a pre-existing small-donor base.
But as the former running mate of President Barack Obama, Mr. Biden did have access to the same email list that raised so much money for the ticket in 2008 and 2012. The fund-raising power of an email list atrophies relatively quickly, according to digital campaign experts, and seven years is a particularly long time to lie fallow.
Mr. Biden’s campaign said Friday that it was “unprecedented” to collect 65,000 donations from people not already on campaign email lists.
Over all in the first quarter of 2019, Mr. Sanders touted more than 525,000 contributors. Mr. O’Rourke had more than 163,000, followed by Mayor Pete Buttigieg of South Bend, Ind. (158,000), Senator Kamala Harris of California (138,000) and Senator Elizabeth Warren of Massachusetts (135,000).
Mr. Biden has the advantage of national name recognition and broad popularity among Democrats. But he is also expected to quickly assemble a robust staff that must be paid.
On Thursday, his campaign announced 26 “key campaign hires” who will work for Mr. Biden at the national level, and it has even more people lined up in the states that will begin the nominating contest: Iowa, New Hampshire, Nevada and South Carolina.
[Read more: Mr. Biden declined to directly apologize to Anita Hill on Friday.]
Mr. Biden spent his first evening as a presidential candidate at the Philadelphia-area home of David L. Cohen, a top executive at Comcast and a former political operative who is one of the Democratic Party’s leading fund-raisers.
Several prominent Pennsylvania politicians were listed as the event’s hosts, who also included Daniel J. Hilferty, the chief executive of the major health insurer Independence Health Group, the parent of Independence Blue Cross.
“It’s gauche to talk about money, so I’m not going to talk about money,” Mr. Cohen said at the fund-raiser, according to a recording of his remarks. “But all I’m going to say is that once again this group has produced an event that is off the charts, beyond anyone’s expectations.”
Mr. Biden’s rivals took note of his entry into the race. Ms. Harris, Mr. O’Rourke, Mr. Sanders, Ms. Warren, Senator Cory Booker of New Jersey, former Mayor Julián Castro of San Antonio and Gov. Jay Inslee of Washington all emailed supporters with Mr. Biden’s name in the subject line to gin up their own donations.
Mr. Sanders and Ms. Warren delivered pointed messages about how Mr. Biden spent his first evening as a candidate. “How did Joe Biden raise so much money in one day?” Ms. Warren’s team wrote. “Well, it helps that he hosted a swanky private fundraiser for wealthy donors at the home of the guy who runs Comcast’s lobbying shop.”