Fewer than one in seven Massachusetts voters is a Republican, so you'd think the minority party would rally around its standard-bearer and top officeholder, acting Gov. Jane Swift.

Think again.

In the famously divided Massachusetts Republican Party, Salt Lake Olympic chief Mitt Romney's expected bid for governor has embarrassed Swift and divided a party that to begin with only claims 14 percent of the state's voters.

And that's before Romney's campaign has even begun.

Romney, whose father was governor of Michigan and who returned to Massachusetts on Sunday after three years in Utah, had previously said he wouldn't challenge an incumbent Massachusetts governor, but that changed after Swift's poll numbers plummeted.

"Considering the tiny percentage of voters who identify thesmelves as Republicans, it's incredible that the Republicans are like wolverines eating their own," said Tobe Berkovitz, a Boston University communications professor who consults for Democratic candidates but is uncommitted in the governor's race.

Only about 14 percent of Massachusetts voters identify themselves as Republicans, and the state's 12 congressional seats are all held by Democrats. But Republicans have held the Governor's Office since 1991.

Rob Gray, a GOP strategist, said Republican primaries in recent years, including the governor's race in 1990 and 1998, after which Republicans went on to defeat Democratic candidates, showed the party is strengthened by hardfought primary battles.

"Republican candidates have a better chance of winning in November if they've won a primary," he said. "Competitive primaries have proven to be a bonus to the Republican Party."

Division among state Republicans is hardly new. Some remember the bruising intraparty battle between supporters of Arizona Sen. John McCain and Texas Gov. George Bush in the 2000 presidential election.

Massachusetts Republicans overwhelmingly favored McCain in the primary, 64 percent to 32 percent, but then-Gov. Paul Cellucci campaigned hard for Bush. That support won him an ambassadorship to Canada, and pushed Swift into the Corner Office.

Others remember the harsh 1998 Republican primary campaign for governor between Cellucci and then-Treasurer Joseph Malone.

More recently, some Swift supporters jumped ship to the Romney camp after she denied parole last month to Gerald Amirault, who was convicted in 1986 of molesting children at a Malden day care center.

Former state Republican Party Chairman James Rappaport -- who is now running for lieutenant governor, against Swift's wishes -- once made a telling observation about his own party.

"There's an old adage: the smaller the boat, the meaner the rats," Rappaport said last year. "There's no question that's been the case here in Massachusetts."

Swift campaign spokesman Dominick Ianno said the best thing for the Republican Party is to have a governor like Swift who protects the taxpayers. He declined to comment on the divided state party.

But Phil Johnston, chairman of the state Democratic Party, pointed to the $2 million Swift has in her campaign account -- an amount which will surely rise -- and said Swift is a much better campaigner than governor, which will hurt Romney in a tough primary fight.

"It's very clear there's going to be a bloodbath on the Republican side," Johnston said.

Ian Bayne, Republican Committee chairman in Somerville and a Romney supporter, disagreed that the "Draft Mitt" campaign is an embarrassment to Swift.

"This isn't an embarrassment to anyone," he said. "You've seen the poll. We're not divided in two. We're divided maybe nine-tenths to one-tenth."

He said Romney and Swift's supporters would rally behind whichever candidate wins the primary.

"What doesn't kill you makes you stronger," he said.