Sen. Bernie Sanders raised $34.5 million in the final three months of 2019 for his White House bid, his campaign said Thursday — a massive sum fueled by his online fundraising machine that may send a financial jolt throughout the Democratic race.

Sanders raised more than $96 million in 2019 alone, and his fourth-quarter total is one of the biggest quarterly hauls reported by a presidential candidate at this point in the campaign.

The fourth-quarter total was one of the clearest signs yet of the momentum Sanders has picked up in recent months.

He has been drawing large and enthusiastic crowds at campaign events, including more than 14,000 at a rally with Rep. Alexandria Ocasio-Cortez (D-N.Y.) in southern California last month, according to the campaign’s estimate. And he sits at or near the top of recent polls in Iowa and New Hampshire, the first two states on the nominating calendar.

The Vermont senator’s standing in the race less than five weeks before the Iowa caucuses marks a remarkable political revival for a candidate who struggled to gain traction over the summer and suffered a heart attack in October that sidelined him from the race and prompted some supporters to wonder if he would even continue his campaign.

Since that time, Sanders has racked up endorsements from prominent figures on the left, including Ocasio-Cortez, a rising liberal star who has campaigned for him in Iowa, California, New York and Nevada.

And as other candidates have modulated their pitch to voters and revamped their policy platforms, Sanders has hewed to the same topics he has long championed: making a pitch to enact a Medicare-for-all health-care system and taking on the wealthy and powerful with new taxes and regulations.

Meanwhile, President Trump’s reelection campaign continues to grow, raising $46 million in the final quarter of the year and entering 2020 with $102.7 million in cash, officials said. Those figures do not include the money raised by the Republican National Committee in support of Trump’s reelection.

Sanders’s fourth-quarter total underscores the strength and sophistication of his online fundraising program, cultivating a loyal base of low-dollar donors from across the county that have propelled him ahead of his rivals in the money chase.

Candidates have until Jan. 31 to file fundraising reports with the Federal Election Commission, but those with impressive figures typically share their totals soon after a quarter ends.

It is unclear yet how much money his campaign spent in the final three months of 2019, or how much he has heading into the Feb. 3 Iowa caucuses and beyond. Those figures will be made public on Jan. 31.

The campaign raised more than $18 million in December alone, its best fundraising month to date, officials said. The average donation in the fourth quarter was $18.53, they said.

His campaign said Wednesday it surpassed 5 million donations — a milestone Sanders did not reach in the 2016 campaign until after Super Tuesday, officials said.

In the final days of the quarter, the campaign peppered supporters with email appeals asking them to give $2.70 repeatedly to help the campaign reach its goal of 5 million donations.

The campaign drew money from 40,000 new donors on the final day of the quarter, and nearly 300,000 new donors throughout the quarter, officials said.

Campaign manager Faiz Shakir said Sanders is building a fundraising machine that could compete in the general election with Trump, who has built a powerful small-dollar donation operation and has already raised and spent record amounts on his reelection campaign.

Sanders “is proving each and every day that working class Americans are ready and willing to fully fund a campaign that stands up for them and takes on the biggest corporations and the wealthy,” Shakir said in a statement. “You build a grassroots movement to beat Donald Trump and create a political revolution one $18 donation at a time, and that’s exactly why Bernie is going to win.”

Sanders campaign officials said they did not transfer any money from other federal accounts in the final three months of 2019. The campaign transferred a total of $12.7 million in previous quarters.

While Sanders is flexing his fundraising muscle, he nevertheless faces some potential hurdles in the weeks ahead. At 78, Sanders is the oldest candidate in the race, and he has faced concerns from some voters about his age. He has sought to put those to rest, releasing a letter from three of his doctors Monday saying that he sustained “modest heart muscle damage” stemming from his Oct. 1 heart attack but is in good health and capable of doing the job.

And while Sanders has been building steam as Sen. Elizabeth Warren (D-Mass.) has declined, he is still faces tough competition from former vice president Joe Biden, who leads in many national polls and is competing with Sanders for many of the party’s working-class voters.

Sanders has also used fundraising as a way to differentiate himself from his rivals, contrasting his reliance on small-dollar donation with his opponents’ courting of the rich.

He has frequently pointed out that he does not have or need a super PAC — a knock at Biden, whose supporters started one late last year — and has accused former New York mayor Mike Bloomberg of trying to buy the election with his personal fortune. Like Warren, Sanders has attacked Pete Buttigieg for raising money from wealthy patrons in an upscale California wine cave.

Three other Democratic candidates released their fundraising totals in the new year, providing a sense of how wide-ranging the results were in the final months of the year.

Businessman Andrew Yang, an outsider candidate in the Democratic race, said he raised $16.5 million in the final three months of the year, a huge improvement in his fundraising strength since he entered the race. The political novice raised under $2 million in the first quarter of 2019.

Buttigieg, the former mayor of South Bend, Ind., reported raising $24.7 million. Rep. Tulsi Gabbard of Hawaii announced raising about $3.4 million.

Warren announced last week that she had raised at least $17 million, asking her supporters to meet a goal of $20 million for the quarter. Earlier this week, the campaign of Sen. Cory Booker (D-N.J.) said he eclipsed his third-quarter haul of $6 million.