Getty Images
CNN  — 

President Joe Biden outraised – and dramatically outspent – the campaign of Republican rival Donald Trump last month, new campaign reports filed Saturday show, raising questions about how long the president’s political team can operate at full throttle if donations dry up.

Some of the Democratic Party’s big-dollar donors have raised alarms about Biden’s poor performance at last month’s presidential debate, and he faces growing calls from elected officials to abandon his bid for a second White House term.

Biden’s campaign stepped up its spending in June, the new filings with the Federal Election Commission show, plowing through more than $59 million as it advertised heavily. His principal campaign committee entered July with nearly $96 million remaining in its bank account – a substantial sum but not enough to sustain June’s blistering spending pace for long without fresh cash infusions.

By contrast, Trump’s campaign spent just shy of $10 million, leaving $128 million in its war chest.

View this interactive content on CNN.com

The Republican National Committee, meanwhile, raised nearly $67 million in June – one of its strongest fundraising months in recent years, far surpassing the $39.2 million collected by the Democratic National Committee last month – as Trump’s political apparatus built up a cash advantage over Biden and the Democratic Party heading into July and the general election showdown.

Biden’s campaign aides argue that they have capitalized on the fundraising advantage that the president held during the early months of this year to build out a robust ground operation in key battleground states that will help them prevail. And they said the campaign collected $38 million in the four days following Biden’s widely panned debate performance. The reports filed late Saturday, however, include only the final few days of last month after the June 27 faceoff in Atlanta. The full impact of the debate – and other key campaign milestones, including the just-concluded Republican National Convention and the announcement of Ohio Sen. JD Vance as Trump’s running mate – won’t be evident until the campaigns file fundraising and spending details with federal regulators in August.

As CNN has previously reported, some donors – fearing a Republican rout in November should Biden remain atop the ticket – are withholding contributions or putting fundraising events on hold as the president faces pressure from some Democrats to exit the race. One fundraiser that proceeded over the weekend in Cape Cod brought in more $2 million, campaign officials said.

The Saturday event was scheduled weeks before the party’s current turmoil and was headlined by Vice President Kamala Harris, the most likely heir apparent should Biden bow out of the race.

“We are going to win this election,” Harris told Saturday’s crowd, asking them to spread that message to their friends.

Many campaign finance experts say that, should Harris become the nominee, any money remaining campaign’s bank accounts would transfer to her political operation because she already is part of the ticket.

But – in a preview of the likely legal fights that would erupt over a Biden departure – some Republican lawyers disagree, arguing that under some interpretations, Biden and Harris must be formally nominated by their party before any money could be shifted.

“If President Biden is committed to passing the torch to his vice president, and wants to be able to seed her campaign with the current Biden for President campaign war chest, he’ll first have to become his party’s legal nominee,” veteran Republican election lawyer Charlie Spies wrote in a recent op-ed in The Wall Street Journal.

Trump’s conviction drove contributions to new high

Although Biden outraised his Republican rival last month, filings in recent days underscore how much Trump has seized on his legal troubles as a fundraising tool.

Contributions to Trump’s political operation soared on the day of his conviction in the New York hush money case on May 30 – when three joint fundraising committees reported receiving $19 million in donations above $200, according to a CNN analysis of filings in recent days with the Federal Election Commission.

Trump was convicted by a Manhattan jury on 34 counts of falsifying business records to cover up a hush money payment to an adult film star. He and his allies have sought to characterize the conviction as politically motivated.

May 30 marked the strongest fundraising day of the year for Trump through June 30, the analysis shows.

View this interactive content on CNN.com

CNN analyzed itemized contributions – those from donors who gave more than $200 – to determine the daily fundraising haul of Trump’s joint fundraising committees with the Republican National Committee and state party committees. A share of the proceeds from one of those committees, the Trump 47 Committee, also benefits a leadership PAC that has helped underwrite legal expenses for Trump and some of his allies.

That leadership PAC, Save America, reported paying more than $827,000 legal expenses and carried another $1.64 million of legal debt into July, according to its FEC filings Saturday.

Trump’s campaign, meanwhile, has consistently spent far less than Biden’s.

The lion’s share of its expenditures in June went to direct mail expenses, according to the filings. Trump’s team is relying heavily on conservative super PACs for data and field work to help find a path to victory in battleground states – following a recent Federal Election Commission ruling that allows greater coordination between candidates and super PACs on costly door-to-door canvassing work.

Deep outside pockets

Saturday’s filings show that the leading pro-Biden super PAC, known as Future Forward or FF PAC, ended June with nearly $122 million in its coffers. Nearly half the $32.8 million the PAC took in last month came from the group’s nonprofit arm, which does not disclose its donors.

Other large donors in June included LinkedIn co-founder Reid Hoffman ($3 million), Google ex-chief executive Eric Schmidt ($1.6 million), and James Murdoch, the son of Fox News mogul Rupert Murdoch, and his wife Kathryn ($1 million total for the couple).

A super PAC backing Trump’s candidacy, MAGA Inc., meanwhile, entered July with nearly $114 million in available cash.

Two-thirds of the $22.5 million that it raised last month came from just three donors who each wrote checks for $5 million: hotelier Robert Bigelow; Linda McMahon, who ran the Small Business Administration during Trump’s White House tenure and had a speaking slot at his nominating convention; and tobacco giant RAI Services.

CNN’s Edward-Isaac Dovere and Samantha Waldenberg contributed to this report.