Former President Donald J. Trump had the best fund-raising month of his 2024 campaign now that he’s working in tandem with the Republican National Committee, pulling in $65.6 million in March, the party announced on Wednesday.

The party said that Mr. Trump, the R.N.C. and their shared accounts now had $93.1 million cash on hand entering April — roughly double what they had a month earlier.

“Our campaign, working together with the R.N.C., has been steadily ramping up our fund-raising efforts, and our March numbers are a testament to the overwhelming support for President Trump by voters all across the spectrum,” Susie Wiles, one of Mr. Trump’s top strategists, said in a statement.

Mr. Trump has been privately meeting with a number of billionaires and potential financiers at Mar-a-Lago over the past month. And in his recent takeover of the R.N.C., his team moved all of the finance and digital staff to Florida.

One reason Mr. Trump was able to bring in so much cash so quickly has to do with the joint accounts he now operates with the party. Those joint accounts are allowed to take in far larger donations — one of them can take in checks of as much as $814,600. During the primary, Mr. Trump had been limited to raising $6,600 for his campaign.

In recent days, Mr. Trump has shifted how new dollars that are donated are divided. During the primary, Mr. Trump made it so 10 cents of every dollar went to his PAC, Save America, money that has mostly been used to pay for legal fees related to investigations and his four indictments.

Now Mr. Trump is directing 10 cents of every dollar given by small donors not to his PAC but to the R.N.C., through one of the new shared accounts called the Trump National Committee. And although Mr. Trump is no longer directing a share of small donations to his PAC, the biggest donations will land in a separate shared account called the Trump 47 Committee, which directs $5,000 of every large contribution to his PAC even before the party gets any cash.

The March numbers will help Mr. Trump narrow the substantial financial hole he had been in compared with President Biden, who had amassed $155 million with the Democratic Party at the end of February.

“Trump is spending what money he does have on everything but reaching out to the voters,” said Ammar Moussa, a spokesman for the Biden campaign.

Mr. Biden has not yet announced a cash haul in March. The event he held in New York last week with Barack Obama and Bill Clinton raised $25 million, and he also raised more than $10 million in the 24 hours after his State of the Union address.

The Biden campaign has leveraged its early cash edge to announce a $30 million advertising campaign over six weeks. But the president has been trailing Mr. Trump in recent polls.

On Tuesday, a new Wall Street Journal poll found that Mr. Trump was leading Mr. Biden across six of the seven top battleground states. Mr. Trump and Mr. Biden were tied in Wisconsin, the seventh state in the poll.