Barack Obama's heart may be with San Francisco after raking in nearly eight million dollars at three fundraisers in the city Sunday.

He promised a VIP dinner crowd -- many of whom paid $28,500 to attend -- that he would win the presidency in November. But he told them to expect a tough battle with Republicans in the meantime.

He said Republicans "know they can't win on the issues." Instead, he said they'll try to "scare" people about him -- saying things like "he's risky" and " We're not sure. "

In July, Obama brought in 51 million dollars to John McCain's 27 million. But the Obama campaign has also been spending at a rapid clip. Obama turned down public funding for the general election campaign, which requires him to keep up a robust fundraising schedule for the fall.