In the month of March, Sanders brought in $44 million, beating its record from February of $43.5 million.
Sanders’ campaign, which unlike Hillary Clinton's is not boosted by an outside super PAC, said in a press release that the total haul for the first quarter of 2016 was more than $109 million.
Last month, the Sanders campaign nearly doubled the fundraising total of Clinton's campaign, which brought in $23.5 million. Fewer than one in three of Clinton's dollars last month were raised from small-dollar donors, compared to almost two in three for Sanders.
Still, Sanders faces an uphill climb to the nomination -- he needs to win about 57 percent of the remaining pledged delegates -- and that's without tackling Clinton's massive superdelegate lead.
His campaign said it raised 97 percent of the money this year online and less than 5 percent from donors who gave the maximum amount allowed, according to fundraising documents last month. This means Sanders would likely be able reap quick cash again if he needs it.
Sanders has in the past called his fundraising techniques “revolutionary.”
Recent polling shows Sanders may have a slight advantage in Wisconsin, which holds its primary next Tuesday. But in Sanders' delegate-rich home state of New York, recent polling shows Clinton leading by double digits.
Speaking to a crowd of 8,000 people in Pittsburgh on Thursday, the Vermont senator said he debated for a moment if he should establish a super PAC.
The crowd booed and Sanders replied, “That is exactly what we concluded.”
“We have gone a different way,” he continued. “We have gone to the working class and middle class and said we will stand with you if you stand with us.”