Boosted by a strong quarter and a personal loan to his own campaign, Assembly member Kevin Mullin has taken a fundraising lead in the closely watched race to replace U.S. Rep. Jackie Speier in District 15, according to reports that were filed with the Federal Election Commission Friday.

Mullin reported $374,888 in total contributions over the last reporting period, which stretched from Jan. 1 to March 31. This includes $328,660 in contributions from individuals and $46,228 from political committees.

The strong fundraising numbers have propelled him past his two closest competitors, San Mateo County Supervisor David Canepa and Burlingame City Council member Emily Beach. Both had been ahead of Mullin in fundraising just before the latest reporting period.

The strong quarter brought his overall campaign chest to $620,000 in total receipts, according to the FEC report. This includes $496,864 in contributions from individuals and $58,228 from political action committees. The total also includes the $40,000 that Mullin contributed to his own campaign. Mullin had also loaned $25,000 to the campaign.

Canepa, which had a commanding fundraising lead at the end of 2021, reported $128,474 in contributions over the past quarter, bringing his overall total to $556,873. The total includes $11,600 from political committees, of which $6,600 came in over the last reporting period, according to FEC filings.

Beach raised $168,842 in the first quarter of the year, bringing her campaign total to $445,729. The vast majority of her contributions came from individuals. Her only contribution from a political action committee was a $5,000 contribution from the International Brotherhood of Electrical Workers Political Action Committee.

Gus Mattammal, the lone Republican in the race, found himself in distant fourth with $12,956 in contributions over the last reporting period, bringing his overall total to $29,372. All of these contributions came from individuals.

While most of Mullin's contributions came from individuals, he also received sizeable checks from numerous political and labor groups groups. GenenPAC, the political action committee associated with the biotech giant Genentech, contributed $5,000 to his campaign. So have the United Food and Commercial Workers International Union, Plumbers & Steamfitters Local #467, and Vision For America, a political action committee run by Speier.

Canepa's campaign received $5,000 from the National Union of Healthcare Workers Federal Committee on Political Education. Canepa also received support from businesses and elected officials from across the county, with Millbrae council member Anne Oliva donating the maximum amount $2,900 to his campaign. Others who contributed the maximum amount to Canepa's campaign include restaurateurs John and Elena Duggan; Daisy Li, CEO of Moonstar; Mark Calvano, principal at Calvano Development; and Richard Peterson, consultant with Lighthouse Public Affairs.

Beach, who has been on the Burlingame council since 2015, was boosted by many donations from her hometown, including $2,900 contributions from software developer Jeremy Gordon, preschool teacher Jill Fair and physician Andrea Meskus. She also received the maximum amount from Kevin Taweel, chairman of Asurion, and attorney Todd Brody, among others.

Mattammal's top contributors include Lilian and Thomas Olivieri, Los Altos residents who contributed $2,900 each to his campaign, and Laura Jones Joukavski, CEO of Global Fashion Brands at TechStyle Fashion Group, who also contributed $2,900.

The Mullin campaign celebrated the latest reports, which campaign manager Brian Rogers called "undeniable proof" that Mullin is in the strongest position to prevail in the race for Speier's seat. Mullin, who kicked off his canvassing operation on Saturday morning in downtown San Mateo, told an assembled group of volunteers and campaign supporters that the campaign believes he is now considered the frontrunner in the race.

"The polls say that, the campaign donations say that. That's all good, but we still need to go out there and win it on the ground," Mullin said.

Canepa said in an interview Friday that he believes his campaign is outworking Mullin's and that his opponent's numbers are inflated by his own contributions.

"I just feel that we're in a much, much better place than he is," Canepa said.

Canepa also touted the fact that his campaign raised a total of $558,000 while remaining "corporate-PAC-free." In a tweet, he noted that his grand total remains "the highest out of all the candidates (not counting $65,000 that an opponent gave to his own campaign)."

The four candidates are vying to represent an open seat in a recently redrawn district that stretches from a southern portion of San Francisco in the north to Redwood City and a section of Menlo Park in the south and that encompasses cities east of the U.S. Highway 280.