Joe Biden on Saturday launched a $12 million ad buy -- the largest paid media blitz of his campaign -- that's fueled by a big fundraising windfall since his campaign's comeback last week.

Biden will spend $8 million on TV with the rest of the money spent on radio and digital platforms. The ads will air across six states that vote in the next two weeks: Michigan, Missouri, Mississippi, Florida, Illinois and Ohio, his campaign announced.

Biden, who has lagged his rivals in fundraising for much of the campaign, got a boost in donations following his big win in South Carolina and victories in 10 of the 14 Super Tuesday states.

Biden announced Friday he'd raised $22 million in the last five days.

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One ad, called "Service," features former President Barack Obama's January 2017 speech when he honored his former vice president with the Medal of Freedom.

A second ad touts Biden's Super Tuesday victories and defends his record on Social Security, which rival Bernie Sanders has gone after in a separate ad.

Biden this week touted the big turnouts he's garnered -- especially in Virginia, which topped 2008 levels -- and said he wants to be the force to unify Democrats.

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“What we can’t let happen is let this primary become a negative bloodbath," Biden said Friday when he called in to a fundraiser. "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. But we can’t tear this party apart and re-elect Trump. We have to keep our eyes on the ball."