Joe Biden is teaming up with former primary rival Sen. Elizabeth Warren on Monday evening.

Their mission: raise a lot of campaign cash.

Tickets for the virtual fundraiser – the first time the former vice president and the progressive champion from Massachusetts are joining forces to formally raise money – range from a low of $250 up to $100,000.

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Warren is far from the first former 2020 Democratic presidential nomination rival who’s teamed up with Biden to haul in big bucks since he became the party’s presumptive presidential nominee. Sens. Kamala Harris of California, Amy Klobuchar of Minnesota, Cory Booker of New Jersey, and former South Bend, Ind., Mayor Pete Buttigieg have all co-hosted fundraisers with Biden the past two months.

The efforts by these former White House hopefuls has helped Biden fill his campaign coffers. Biden announced on Monday and his campaign and the Democratic National Committee combined raised $80.8 million in May.

But Warren’s a different case, as she repeatedly forswore top-dollar fundraisers with wealthy donors during her White House bid.

The senator held high-dollar fundraisers during her 2018 Senate reelection campaign. However, along with fellow populist and 2020 rival Sen. Bernie Sanders of Vermont, she eschewed them early in 2019 soon after launching her campaign for the Democratic presidential nomination. While Sanders has sent out fundraising emails in conjunction with the Democratic National Committee on Biden’s behalf, he has not teamed up to host a virtual fundraiser with the former vice president.

During her bid for the White House, Warren was critical of rivals who held top dollar fundraising events.

After Biden brought in $6.3 million on the day he announced his candidacy in April of last year -- with part of the haul coming from a fundraiser at the home of a Comcast executive -- Warren slammed him for attending a “swanky private fundraiser.”

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And “wine cave" became part of the campaign vernacular last December after Warren, during a primetime primary debate, targeted Buttigieg for holding a fundraiser in a ritzy wine cave at a Napa Valley vineyard in California.

President Trump's re-election campaign - noting that Warren as late as early March criticized Biden as a "Washington Insider" - took aim at both the senator and the former vice president.

Calling Warren a "hypocrite" who "sold out to the DNC establishment," Trump campaign manager Brad Parscale tweeted that the senator "once said that Biden is too much of a Washington insider to change anything in the swamp. Warren has sold out but it's still true."

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The Biden-Warren fundraising event comes as the senator is considered one of the contenders to be the former vice president’s running mate. And it comes three day after a large group of more than 100 progressive activists and celebrities – including Jane Fonda – sent a letter to Biden urging him to choose Warren as his pick for the Democratic Party’s 2020 vice presidential nominee.

Fox News' Andrew Craft contributed to this report