Republican presidential candidate Ben Carson speaks in Manchester, N.H. (Mary Schwalm/AP)

Retired neurosurgeon Ben Carson, an underdog Republican presidential candidate with a tea party support base, raised more than $8.3 million between April and June, his campaign said Wednesday, making him the first GOP hopeful to announce his numbers publicly.

Carson, the only major African American candidate in the Republican field, raised about $10.5 million since he launched an exploratory committee on March 3, according to campaign spokeswoman Deana Bass. Since that time, he has collected donations from 151,000 donors, Bass said.

The Associated Press first reported Carson's totals. His numbers lagged well-behind Democratic front-runner Hillary Rodham Clinton, who hauled in $45 million between April and June.

The second-quarter fundraising deadline passed at midnight June 30. Candidates have until July 15 to report their totals to the Federal Election Commission, but many are expected to publicly release their topline numbers before then.

Many candidates also have supportive super PACs, which can accept unlimited donations. Such groups must report their totals to the FEC by July 31. They may release their totals tandem with the campaigns they support, in order to provide a snapshot of the total money that was raised for that candidate.

Polls show Carson, who is running as a staunch conservative and outspoken critic of President Obama, running toward the front of the packed Republican field. But his campaign has been seized by early turmoil and staff exits, ThePost recently reported, raising questions about the long-term viability of his bid.

Carson's campaign did not immediately say how much cash on hand it had at the end of June. Such figures are useful in looking at how quickly a campaign is burning through its money.

Bass would only say the cash on hand amount was "a lot."

Asked whether any part of Carson's total was self-funded, Bass said he made a $25,000 loan to the campaign in the run-up to launching his exploratory committee.