In 2004, supporters of Romney formed the Commonwealth Political Action Committee, which has contributed $218,000 to 225 GOP candidates and party organizations in 17 states. In recent months he has spoken to Republican audiences in Iowa, Michigan, Missouri and South Carolina. "Mitt is testing the waters," says his friend and political consultant Michael Murphy. And the waters in South Carolina are feeling just fine, to judge by what Rick Beltran, chairman of the Spartanburg County GOP, told me. Beltran says the speech Romney gave in Spartanburg on Presidents Day impressed the audience of about 400, which was made up mostly of "hard R's, the kind of people he'd need to attract to become president."

Romney would have to stand for re-election in 2006 if he were to stay on as governor. He says he'll decide this fall whether to run again. "There are factors that I will consider before making a final decision," he told me during an interview in his office in Boston. Some of those "factors" have to do with a presidential bid. If Romney ran for a second term, and the state's voters denied it, he'd be an implausible presidential candidate. On the other hand, if he won he'd quickly find himself faced, if he still wanted to run for president, with whether he should resign.

Romney says he's been told "the demands of running for national office today are such that the two years prior to the general election you are basically running full time. There are probably some states where the people would say, 'Hey, we are going to elect you as governor, and we don't care if you do something else full-time for two years.' But Massachusetts isn't one of those states, New York isn't, Michigan isn't, Ohio isn't." (Texas is one, where George W. Bush ran for re-election in 1998 having told voters he might run for president in 2000.)

Romney also has noticed that some rumored 2008 candidates wouldn't be constrained by obligations of office—Bill Frist, who's giving up his Senate seat in 2006, and Rudy Giuliani, who has been the former mayor of New York City for over three years now. "If we look back in history," says Romney, "Ronald Reagan wasn't a sitting governor" when he ran for president, "Howard Dean wasn't a sitting governor. They had finished their responsibilities and were able to focus on the race." Romney also happened to criticize John Kerry for not resigning as senator while he ran for president. "My guess," says Romney, "is that if I were to try that, someone would notice what I'd said before."