(CNN) - Democratic Senate hopeful Elizabeth Warren raised more than $8.6 million in the last three months, her campaign announced Monday.
The second quarter figure surpassed her first quarter amount of $6.9 million. She now has $13.5 million cash on hand, according to the campaign.
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Warren is locked in a bitter race against incumbent Republican Sen. Scott Brown, who's fighting to keep the seat he won in a 2010 special election to replace the late Ted Kennedy.
Warren, who served as an adviser in the formation of the Consumer Financial Protection Bureau, has strong backing from national Democrats, including President Barack Obama. The president praised the candidate at a recent event in Boston.
Her campaign said they "experienced a surge in grassroots donations" last quarter, with 81% of donations amounting to $50 or less and more than half at $25 or less.
"Elizabeth Warren has fought hard to create a level playing field for middle class families. It is those men and women who are fueling this campaign," said Mindy Myers, Warren's campaign manager.
While money seemed to pour in last quarter, Warren faced some of her toughest scrutiny during the same window of time, taking heat over allegations that she claimed Native American ancestry as a method for career advancement.
Clarifying, Warren, a Harvard law professor, confirmed she told employers at Harvard and University of Pennsylvania of her heritage, but noted she did so only after she was hired. The story, however, remained in the headlines for weeks, as Brown's campaign continued to call for her to answer questions about the issue.
The Warren campaign also said June marked the best fund-raising month overall, with $3.1 million raised.
Brown's team argued Warren's war chest largely depends on "out-of-state" donors and "extreme special interests."
"Ultimately, however, elections are decided by the voters based on competing visions for our future, and Scott Brown will have the resources he needs to share his pro-jobs message and independent record with voters across the Commonwealth," said Brown spokeswoman Alleigh Marre. "No amount of money can wash away Professor Warren's support of job-crushing tax hikes that would devastate our economy, especially in the wake of Friday's incredibly weak employment report."
While Brown's campaign is not yet releasing its numbers, the incumbent brought in $3.4 million during the first three months of this year and had $15 million in the bank at the end of March.