SAN DIEGO - Mitt Romney presents himself as the man to fix the U.S. economy but his determination to do so doesn’t quite stretch to signing up as vice president if his chief rival for the Republican nomination, Sen. John McCain, wins the race.

Campaigning in California, the former Massachussets governor stressed his business acumen in comparison to McCain who he said had shown again and again that the economy was “not his strong suit.”

“I think the other day, by the way, he said he would choose a vice president who had a lot of knowledge about the economy because of his own relative weakness in that area,” Romney told a rally in San Diego.

“But I’ve got some bad news. I’m not available for VP.”

The Harvard-educated former business executive co-founded the private equity firm Bain Capital and has repeatedly portrayed himself as more of an economics expert than McCain, a Vietnam veteran Romney described as “an American hero.”

Romney said it was time for a change in Washington where politicians had failed to address economic challenges for decades. 

“Senator McCain is a fine guy but he’s been there 25 years and if he hasn’t been able to get it done in a quarter of a century, why give him a chance at being president?”

PICTURE: Reuters/Danny Moloshok: Republican presidential candidate and former Massachusetts Governor Mitt Romney thanks supporters in Fountain Valley, California