President Biden’s campaign expects to collect more than $28 million at a gala Los Angeles fund-raiser packed with celebrities on Saturday night in a Hollywood show of force.

Mr. Biden left a meeting of world leaders in Italy on Friday to fly to Los Angeles for the dinner, which will feature former President Barack Obama, the actors George Clooney and Julia Roberts and the late-night talk show host Jimmy Kimmel. Air Force One was expected to land in Washington only long enough to refuel for the continuing flight.

The travel across 10 time zones illustrated the competing presidential and political demands on Mr. Biden’s time as the campaign against former President Donald J. Trump accelerates. Aides said the taxing schedule made clear that even at age 81, he still demonstrates the endurance to manage his many duties.

The $28 million haul anticipated from Saturday’s event was set to break a party record, overtaking the $26 million Democrats brought in from a fund-raiser in March in New York featuring Mr. Biden along with Mr. Obama and former President Bill Clinton.

While Mr. Biden and the Democrats have outpaced Mr. Trump’s team in donations for much of the campaign, Republicans pulled in $50.5 million at an event in Palm Beach, Fla., in April, and said they raised a total of $141 million in May, matching what Mr. Biden and Democrats raised in March and April combined.

Tickets for the Democratic event at the Peacock Theater run from $250 for grass-roots supporters to $500,000 for a four-seat package. The film and television industry has long been a financial bulwark for the Democrats, but organizers hoped to use Saturday’s fund-raiser to bolster Mr. Biden’s coffers and demonstrate his strong support among some of the nation’s most recognized figures.