Sen. Elizabeth Warren, D-Mass., is an underestimated political force among Democrats in the 2020 presidential primary, according to Donna Brazile.

Warren raked in millions in donations in the second quarter of 2019 and has been holding engaging rallies across the country, Brazile said Monday on "The Story."

"She's a sleeper in this race -- we better pay attention," Brazile claimed. "She has so much grassroots support and energy."

The Fox News contributor and former DNC chairwoman added Warren was succeeding in firing up some of the base.

TRUMP CAMPAIGN, RNC ANNOUNCE $105M FUNDRAISING HAUL, BLOWING PAST DEM CANDIDATES

"Over the weekend, I saw several candidates," she said. "I have to say, she was the one that struck a chord with the audience, along with Kamala Harris and Mayor Pete," referring to Pete Buttigieg, the mayor of South Bend, Indiana.

Additionally, Brazile claimed Warren's fundraising haul proved she has enough resources to spread her campaign message.

"I do believe that she, like many of the others, is running a terrific campaign so far."

Last week, the Trump campaign announced its re-election operation raised a whopping $105 million in the second quarter -- a figure that blew past what Democrats including Warren have been pulling in.

As for their war chest, the campaign reported it had $100 million in cash on hand.

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President Trump raised a large chunk of that -- $24.8 million -- in the 24 hours after his 2020 re-election campaign launch last month. The figures revealed last Tuesday indicated that fundraising has been steady throughout the quarter.

“Our massive fundraising success is a testament to the overwhelming support for President Trump,” the president's campaign manager, Brad Parscale, said in a statement Tuesday. “No Democrat candidate can match this level of enthusiasm or President Trump’s outstanding record of results.”

Fox News's Martha MacCallum and Brooke Singman contributed to this report.