Democratic presidential candidate Joe Biden Joe BidenCast of 'Parks and Rec' reunite for virtual town hall to address Wisconsin voters Biden says Trump should step down over coronavirus response Biden tells CNN town hall that he has benefited from white privilege MORE said Friday that his campaign had raised $22 million in five days amid a surge in support following his South Carolina and Super Tuesday wins.

Biden's victory in 10 of 14 states that voted Tuesday not only resurrected a campaign that had been left for dead just weeks ago but also vaulted the former vice president ahead of Sen. Bernie Sanders Bernie SandersMcConnell accuses Democrats of sowing division by 'downplaying progress' on election security The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Why Democrats must confront extreme left wing incitement to violence MORE (I-Vt.) in the race for delegates for the Democratic nomination.

The former vice president shared his fundraising update on Friday during a call with supporters at a Bethesda, Md., fundraiser and warned of an "increasingly negative" campaign from "Bernie Brothers."

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"What we can't let happen is let this primary become a negative bloodbath," Biden said. "I know I'm going to get a lot of suggestions on how to respond to what I suspect will be an increasingly negative campaign that the Bernie Brothers will run."

"We can't tear this party apart and reelect Trump," he added. "We have to keep our eyes on the ball, in my view."

"Bernie Bros" has been the colloquial term for hard-line Sanders supporters since the 2016 election cycle. Despite Sanders's signature progressive policies, Bernie Bros have frequently received flak for aggressive tactics on social media platforms such as Twitter.

In February, before the Nevada caucuses, supporters raised eyebrows after attacking Nevada's influential Culinary Union on Twitter for saying that Sanders's "Medicare for All" health care plan would strip union members of their existing health care coverage. Sanders rebuked and condemned the actions at the time, calling them "unacceptable."

Sanders's communications director, Mike Casca, pushed back on Biden's comments Friday warning about an "increasingly negative" campaign from those backing the Vermont senator.

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"Tens of millions are uninsured while coronavirus spreads, the planet is warming at an accelerating rate, working people haven't seen a real raise in decades, and Joe Biden is worried about some damn tweets?" he said in a statement reported by CNN.

"Let's try to stay focused on the big issues," he added.

Biden and Sanders will face off in the next round of primaries on Tuesday, with Michigan, Washington state, Missouri, Mississippi, Idaho and North Dakota all voting.

Michigan, with 125 pledged delegates, is the biggest prize of the night, and many believe that a strong performance from Sanders is crucial if he wants to remain competitive in the race.