Democratic presidential candidate Hillary Clinton’s campaign manager Robby Mook acknowledged Thursday that rival Sen. Bernie Sanders (I-VT) raised more donations is January.

“He outraised us in January,” Mook said at a Bloomberg Politics breakfast, according to CBS News. “We’ve been very candid with our online supporters that Senator Sanders’ online supporters have given more often — a higher proportion of his list contributes.”

BIG: @HillaryClinton just announced she was outraised by @SenSanders in $ in January. He raised $20m, she raised $15m … — Ed Henry (@edhenry) February 4, 2016

Sanders’ campaign announced on Sunday that the Vermont senator raked in more than $20 million in January. Clinton raised $15 million.

In contrast to Clinton’s fewer but bigger donations, contributions to Sanders’ campaign in January almost entirely consisted of online payments, averaging $27 a person. CBS notes that there were more than 770,000 individual contributions, bringing the total number of individual donations for his campaign to $3.25 million.

Clinton’s campaign reportedly said 95 percent of its donations in January were given in $100 increments or less.

This is the first time that Sanders outraised Clinton in one quarter. Sanders reportedly came close in the July-to-September quarter, raising $25.5 million, finishing just $3 million behind Clinton’s campaign.

The numbers indicate a dramatic rise in Sanders’ fundraising haul over the past three months. He finished in a virtual tie with Clinton during this week’s Iowa Caucus where Clinton declared a victory despite the very small margin between the two candidates; a statistic indicating deep divisions within the Democratic Party itself among its voting class.

Clinton was also the winner of six coin tosses which awarded her six precincts that were deemed a deadlock tie during Monday’s caucus.

While Clinton enjoys the support of an older demographic, Sanders has been championed as the candidate of the millennials.

Follow Adelle Nazarian on Twitter @AdelleNaz.