Fredreka Schouten

USA TODAY

Vermont Sen. Bernie Sanders raised $44 million in March, surpassing his record-breaking February haul as his campaign readies for a round of expensive primary fights this month.

The March numbers bring Sanders' total fundraising during the first quarter of the year to nearly $109 million. More than 97% of that money was raised online, campaign officials said in a new release.

"Working people standing together are going to propel this campaign to the Democratic nomination and then the White House," Sanders said in the statement.

Sanders big haul comes of the heels of his three lopsided wins over Hillary Clinton in Alaska, Washington state and Hawaii last weekend. The Democratic nomination fight heads to Wisconsin on Tuesday and New York on April 19, a state home to the most expensive television advertising market in the country. A whopping 291 delegates are at stake in New York, the largest delegate prize of the month.

While Sanders has claimed momentum from a string of caucus wins in March, Clinton still leads in the delegate math.

Clinton's camp had not released March fundraising numbers as of Friday morning. In an fundraising email Thursday night, she implored supporters to chip in as little as $1. "Even with our delegate lead, we can't underestimate Senator Sanders and his team," Clinton wrote.