Bernie Sanders raised more than $34.5m in the last three months of 2019, his presidential campaign announced on Thursday, a considerable show of strength ahead of the Iowa caucuses early next month.

The massive sum demonstrates Sanders’ enduring ability to draw millions of dollars from a large pool of small-dollar donors. It is also the clearest sign yet that the US senator from Vermont has not only rebounded since his heart attack in October but gained ground in the fiercely contested Democratic primary contest.

Since he entered the race in February, Sanders has raised a total of $96m from more than 5m donations – a new milestone for the campaign at this point in the election cycle.

“Bernie Sanders is closing the year with the most donations of any candidate in history at this point in a presidential campaign,” Faiz Shakir, his campaign manager, said in a statement. “He 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.”

The statement added: “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.”

The campaign’s financial haul is the largest quarterly total of any Democratic presidential candidate so far this cycle – and will likely place him atop the field for this quarter.

Meanwhile, Trump’s re-election campaign raised $46m in the last three months of 2019, a period in which the Democratic-led House impeached the president on charges of abuse of power and obstruction of Congress. The haul gives Trump a sizable fundraising edge over his potential challengers battling for the Democratic nomination.

“Democrats and the media have been in a sham impeachment frenzy and the president’s campaign only got bigger and stronger with our best fundraising quarter this cycle,” Brad Parscale, the Trump 2020 campaign manager, said in a statement. “The president’s war chest and grassroots army make his re-election campaign an unstoppable juggernaut.”

The Trump campaign reportedly begins the year with cash on hand of $102.7m .

Only a few candidates have announced their latest fundraising totals yet. Pete Buttigieg, the former mayor of South Bend, Indiana, who is surging in the early states, announced on Wednesday that he had raised $24.7m in the fourth quarter. The tech entrepreneur Andrew Yang announced on Thursday that his campaign raised $16.5m in the fourth quarter, his campaign said, a figure that blows past the nearly $10m he collected in the previous quarter. Meanwhile, the congresswoman Tulsi Gabbard of Hawaii raised about $3.4m in the fourth quarter, her campaign said on Wednesday.

Sanders received 1.8m donations in the fourth quarter, including contributions from 40,000 new donors who contributed on the final day of the quarter, his campaign said. It added that December was the campaign’s “single best fundraising month to date”. He raised $18m from more than 900,000 last month.

Sanders’s total of more than $34.5m was an improvement from the third quarter, when he brought in $25.2m. He raised $18m in the second quarter and $18.2m in the first quarter.