For several hours on Saturday evening, drivers on a typically scenic stretch of Palm Beach, Fla., had their views of the coast obscured by a line of luxury vehicles whose owners were mingling inside a mansion across the road.

The shoreline-blocking Range Rovers, Aston Martins and Bentleys hinted at the deep-pocketed donors attending a fund-raising dinner for former President Donald J. Trump’s presidential campaign, which it and the Republican National Committee said had raised more than $50.5 million.

The event, hosted by the billionaire John Paulson at his home, followed a concerted push by the Trump campaign to address a longstanding financial disparity with President Biden and Democrats as both parties gear up for the general election.

The reported total, which cannot be independently verified ahead of campaign finance filings in the coming months, is nearly double the $26 million that President Biden’s campaign said it raised last month at a celebrity-studded event at Radio City Music Hall in New York City.

Susie Wiles and Chris LaCivita, senior advisers to the former president who are effectively his campaign managers, said in a statement that the total made it “clearer than ever that we have the message, the operation and the money to propel President Trump to victory on November 5.”

Mr. Trump’s event, just down the road from his home at Mar-a-Lago, was in some ways a less flashy affair than its Democratic antecedent, one that traded Hollywood star power and New York City energy for a warmer clime, an abundance of palm trees and the manicured lawns typical of an island refuge for the moneyed elite.

But expectations ahead of the dinner were high, with Mr. Paulson and Trump campaign advisers vowing to outdo the Biden event. An invitation obtained by The New York Times suggested a contribution of $814,600 or the comparatively more modest $250,000.

The money raised, according to the invitation, will be directed to the Trump 47 Committee, a shared fund-raising agreement among the Trump campaign, the Republican National Committee and roughly 40 state parties. Such joint accounts can take in checks of as much as $814,600.

Mr. Trump, who has long had a penchant for superlatives, had predicted on his social media site, Truth Social, that the dinner would be the “biggest night in Fund Raising of ALL TIME!!!”

The former president arrived shortly before 7 p.m. with his wife, Melania Trump, who has made sparse appearances at political events during her husband’s third presidential campaign. “This has been some incredible evening before it even starts,” Mr. Trump said before posing for a photo with Mr. Paulson and entering the house.

Around 100 people were expected to attend the dinner, with a number of billionaires on the guest list.

Among the event’s co-chairs were familiar megadonors and Trump allies, including Rebekah Mercer, a major donor to Mr. Trump in 2016; Linda McMahon, a former Trump cabinet official; and Robert Bigelow, who backed Gov. Ron DeSantis of Florida in the Republican primary but in February donated $5 million to Mr. Trump’s super PAC.

Not all of those who wrote checks opted to attend. John Catsimatidis, a New York grocery store chain owner with a long history with Mr. Trump, was a co-chair of the event but said other commitments kept him from being present.

Under the shared fund-raising agreement, the first $6,600 of any contribution will go to Mr. Trump’s campaign. The next $5,000 will go to his Save America PAC, the political account he has used to pay his legal bills. (That amount is the maximum contribution allowed to Save America under federal rules.) The R.N.C. will get the next $413,000, and then will come dozens of state parties.

Mr. Trump and his team have effectively taken over the R.N.C., installing new leadership, pushing through layoffs and restructuring the national party’s operations to align it more closely with the campaign.

Fund-raising has been a major focus of the overhaul, particularly as Mr. Biden and Democrats have banked cash and built a significant financial advantage over the last several months.

The Biden campaign said earlier on Saturday that it, the Democratic Party and affiliated committees had raised more than $90 million in March, and that together they had $192 million on hand going into April. The Trump campaign said it and the Republican National Committee had raised $65.6 million in March, the former president’s best fund-raising month so far, and that they, along with their shared accounts, had $93.1 million on hand.

Mr. Biden’s campaign manager, Julie Chavez Rodriguez, said in a statement that the Democratic fund-raising numbers stood in “stark contrast to Trump’s cash-strapped operation.”

Mr. Biden’s totals were helped in part by the glamorous event in front of 5,000 donors at the storied Radio City Music Hall. Mr. Biden and two of his Democratic predecessors, former Presidents Barack Obama and Bill Clinton, were interviewed by the late-night host and comedian Stephen Colbert.

A number of musical guests, including Queen Latifah, Lizzo and Lea Michele, entertained the crowd.

The special guests billed on the invitation for the Trump fund-raiser were three of his former primary rivals who have since become campaign surrogates and joined him on the trail: Senator Tim Scott of South Carolina, Gov. Doug Burgum of North Dakota and Vivek Ramaswamy, the tech entrepreneur.

Maggie Haberman contributed reporting.