(CNN) - Democratic presidential candidate Barack Obama's campaign raised $66 million in August, the campaign announced Sunday, topping its previous high mark and running well ahead of Obama's Republican rival.
The Obama campaign said more than half a million new donors contributed during the month, when the Illinois senator accepted the Democratic presidential nomination and named Sen. Joseph Biden of Delaware as his running mate. The campaign had more than $77 million cash on hand at the end of August, compared with about $66 million in July.
Obama's previous monthly donation record of $55 million came in February, during his primary battle with New York senator and former first lady Hillary Clinton.
Earlier this month, the campaign of GOP presidential nominee John McCain reported raising $47 million in August. That haul also set a monthly record for the Arizona senator, whose campaign says it received a financial shot in the arm after McCain picked Alaska Gov. Sarah Palin to join the ticket.
McCain has accepted federal matching funds for his general election campaign, giving him $84 million to spend for November. The money comes with strict spending limits, but the Republican National Committee's Victory fund can continue to raise and spend money on his behalf.
Obama has rejected public financing, calling the system "broken" - a decision that frees him to continue raising money for November.