President Biden’s campaign coffers are filling up with Hollywood money … including $28 million and counting from a major upcoming fundraising event set to shatter records.

The Prez’s reelection campaign tells TMZ … 46’s campaign has already raised $28 million from Saturday’s fundraising event in Los Angeles, making it the single largest Democratic fundraiser in U.S. history.

Sources with direct knowledge tell us tens of millions of that figure comes from advance ticket sales for Saturday night’s event, which is set to feature a star-studded lineup of celebs … headlined by George Clooney, Julia Roberts, Jimmy Kimmel, Jason Bateman, Jack Black, Kathryn Hahn, Sheryl Lee Ralph, and even Barack Obama.

And get this … we’re told several million of the $28M thus far comes courtesy of small dollar donors — which means a helluva lot of ordinary folks have chipped in toward JB’s cause.

In terms of what exactly is going to be discussed at this fundraiser Saturday — we’re told that a lot of the issues will be tackled … including several pieces of legislation Biden’s gotten passed during his first term. So, it won’t just be celebs schmoozing … it’s brass tacks too.

Bottom line … it’s gonna be a who’s-who for JB, and since POTUS will be in one of the richest parts of the country — his campaign stands to rake in a major amount of dough.

Mind you … the $28 mil we’re told Joe has already raised accounts for money BEFORE the actual evet — at this pace, Joe seems primed to walk away from L.A. with their coffers full.

Stay tuned …