Carson, a retired neurosurgeon who has never held public office, said in a fundraising email to supporters Saturday that his campaign was "on the verge of our biggest month ever -- a whopping $10 million dollars raised." The campaign has previously said
that he raised $9 million total in July and August, and the $20 million figure was confirmed by campaign spokesman Doug Watts.
Carson's numbers cannot be independently verified until he files a report on his finances next month, and it is also not yet known how much money it cost for Carson to raise that $20 million. Heavily reliant on low-dollar fundraising -- donations that are less than $200 -- Carson burned through much of his cash in his opening months on fundraising costs, including building contributor email lists.
But if reached, the $20 million haul would likely outweigh nearly all of his Republican rivals' and give Carson's campaign more staying power than originally expected. Despite his appeal with elements of the Republican grassroots, some GOP operatives have wondered whether Carson could assemble the financial muscle to mount a serious bid for the Republican nomination.
Carson has said that a recent controversy over whether he would support a Muslim for president has energized his money game, saying Wednesday
that "it's hard to even keep up with it."
Carson raised $8.5 million in the spring quarter, two-thirds of it from low-dollar donors. His campaign said it will soon receive its 500,000th donation.
"A $10 million month would be unprecedented for our campaign. It's astounding, particularly when you realize this is all from small donations of $10, $25 and so on," the email read.
The previous fundraising leaders are expected to once again have strong quarters: Jeb Bush, whose campaign raised $11 million in just over two weeks, and Ted Cruz, who collected $14 million over the two quarters that he has been an official candidate.
Carson has yet to show, however, that like Cruz and Bush, he can land high-dollar contributions to his super PAC, which is not subject to donation limits. Carson's main big-money group, One Vote, won't have to file a report until early 2016, but as of last quarter it had only raised $100,000 -- 1,000 times less than Bush's did.
"We¹re expecting to be very competitive with peer groups," One Vote head Andy Yates told CNN last month.