JOHNSTON, Iowa – Republican presidential hopeful Mitt Romney has taken out the checkbook again.

But the former investment banker played coy on Tuesday refusing to reveal how much he has contributed to his own campaign in the quarter ended Dec. 31.

Romney had pumped a total of $17.5 million into the campaign by the end of September, enabling him to spend more on staff and advertising than rivals like former Arkansas Gov. Mike Huckabee and Arizona Sen. John McCain. He is neck-and-neck with Huckabee in Iowa opinion polls and McCain has been gaining on him in New Hampshire.

“I’m sure I made additional contributions in the fourth quarter but I don’t have any numbers for you,” Romney said at a press conference in the home of a supporter.

Campaign spokesman Eric Fehrnstrom confirmed that Romney had contributed to the campaign again but also declined to say how much.

Romney amassed a fortune of between $190 million and $250 million over his career as a business consultant and venture capitalist before he was elected Massachusetts governor in 2002. And he has not hesitated to spend that money on his presidential bid.

Candidates must disclose their fundraising figures by the end of January. Democratic front runners Hillary Clinton and Barack Obama announced on Tuesday that they had raised over $100 million in 2007.

Romney is not so forthcoming.

“We’re not going to get into the numbers probably until some time in the middle of the month. Right now, we’re focused on voters,” he said.

– Photo credit: Reuters/Keith Bedford