The Vermont senator reportedly plans to announce on Monday that his campaign has raised $20 million in the past month. That’s on par with, if not more impressive than, Hillary Clinton’s donations. According to the New York Times, Clinton raised $37 million in the last three months before the new year.

The senior adviser to Sanders’ campaign, Tad Devine, told the Times in an interview that the senator’s ability to encourage large amounts of small donations is what sets him apart from past candidates who may have bred similar interest, but were ultimately unsuccessful in their campaigns for financial reasons. Sanders, on the other hand, didn’t hesitate turning down a donation from notorious ex-CEO of Turing Pharmaceuticals, Martin Shkreli.

In the latest Iowa poll, the last before Monday’s caucus, Clinton came in first with 45% of voters’ support, but Sanders was trailing her, dangerously close at 42%. Devine said that any early momentum in Iowa or New Hampshire could translate into even more donation money. He said in the interview, “I’m talking tens of millions of dollars in a period of a couple of weeks.”