Presumptive Republican presidential nominee Mitt Romney last month collected almost $77 million for his campaign, some $17 million more than President Barack Obama.
The Republican National Committee announced the fundraising figures on its Twitter account on Thursday, just a few hours after the Democrats had done the same.
The Romney campaign also announced in a communique that it currently has at its disposal a sum of $107 million, but the Obama team has not revealed the size of its war chest.
The Democrats said that the average donation they received in May was $54.94 and emphasized the increase in donations last month over the $43.6 million they collected in April.
The framework for donations to Obama is the same one that worked so well for him in 2008: contributions no larger than $100 made by a huge number of people.
May was the first month for which the collection figures of the two candidates could really be meaningfully compared, given that Romney only secured the Republican nomination in April.
According to the RealClearPolitics Web site, which prepares an average of the main opinion surveys, with five months remaining until the U.S. presidential election Obama is leading Romney by 47.7 percent to 44.7 percent. EFE