• President Joe Biden's re-election campaign, allied committees and PACs and the Democratic National Committee say they together raised $85 million in May.
• The figure puts Biden's May haul far short of the $141 million that Donald Trump's campaign, allied groups and the Republican National Committee say they jointly raised.
• Biden's May fundraising marked his second-best month, behind March, and left him with $212 million in the bank.

President Joe Biden's reelection effort and the Democratic National Committee raised a combined $85 million in May, according to exclusive data provided to CNBC by the Biden campaign.

The sum marks the president's second-best month this cycle for fundraising, behind only March.

Still, it trailed significantly behind the $141 million that former President Donald Trump's political operation and the Republican National Committee claim to have raised the same month.

The May fundraising left the Biden campaign and allied groups with $212 million in cash on hand at the end of the month, the data shows, up from $192 million at the end of April. A majority of the May fundraising, the campaign says, came from grassroots donors.

"Our strong and consistent fundraising program grew by millions of people in May, a clear sign of strong and growing enthusiasm for the President and Vice President every single month," Biden campaign manager Julie Chavez Rodriguez said in a statement.

"The money we continue to raise matters, and it's helping the campaign build out an operation that invests in reaching and winning the voters who will decide this election."

The Biden team has been using the funds to build out a massive ground-game across the country, announcing earlier Thursday that it had just hired its 1,000th staffer.

The Trump campaign, by contrast, has been slow to staff up in key states, causing concern among some Republican strategists.

The May figures underscore how the presidential fundraising dynamic has shifted in recent weeks in favor of Trump, who has now significantly outraised his opponent in each of the past two months. In April, Trump's allied groups and the RNC raised $76 million to Biden and the DNC's $51 million.

Much of that momentum in May was fueled by small dollar fundraising around Trump's trial and conviction late in the month on 34 counts of falsifying business records to conceal a hush money payment. The campaign said it raised nearly $53 million, or more than a third of their overall total, in the 24 hours after the verdict was announced.

Trump's affiliated super PACs have also been pulling in massive donations. Conservative megadonor Timothy Mellon donated $50 million to MAGA Inc. on the day after Trump's verdict, FEC filings show.

Biden campaign officials highlight how, in contrast to Trump, Biden did not have any major fundraisers or events during the month. May marked the second-best month for grassroots fundraising for Biden's reelection effort, and the best month so far for recurring donations. 

One figure the Trump campaign has not reported this month—and will not be legally required to report until July—is its cash on hand. As of April, the Trump allied campaign's overall war chest was about $60 million smaller than Biden's—$88 million versus $146 million. 

It's not year clear whether Trump's latest fundraising push has helped him build out his cash pile. 

After May's quiet month for Biden, both operations are on track to put up impressive numbers for June: Biden's star-studded Hollywood fundraiser last week raised more than $30 million, while Trump's West-Coast fundraising swing earlier in the month pulled in roughly $27.5 million.