US media reports that a photo with the trio will cost $100,000 (£79,100), while donors will have to shell out at least $250,000 to attend a reception with them.
One veteran Democratic fundraiser claimed that it will be the “largest fundraising event in Democratic history”.
Mr Trump has used the gathering, which brings together three of the four living Democratic presidents – all of whom he has attacked at points in his career – to galvanize his own fundraising efforts.
“DON’T LET OBAMA SPIT IN YOUR FACE!” he said in a text message to registered supporters. Apparently referencing the Democratic event on Thursday, he continued: “Tomorrow they aim to HUMILIATE us. It’s bad.”
In a separate message, he hit out at the “Obama-Clinton cartel” and claimed that the Democrats hope the fundraiser will be the “biggest victory” of their campaign.
In response, the Republican called on “one million pro-Trump patriots” to donate to his election war chest.
Mr Biden has had a strong start to the year in raising funds for the election battle, while his opponent is bogged down in court cases and legal fees.
The president’s campaign had $97.5 million cash on hand at the end of February – more than double that of Mr Trump.
However, commentators point out that Hillary Clinton lost to Mr Trump in the 2016 presidential race despite outspending him two to one.
Tags: Donald Trump Barack Obama spitting face Americans White House calls claims
