Republican presidential front-runner Mitt Romney has been on a glide path toward the 2012 primary elections, serving up a steady diet of soundbites and campaign material attacking President Barack Obama on jobs and the economy.

The easy ride will end if Texas governor Rick Perry jumps into the Republican race -- especially since Perry has the strong record on job creation that Romney, a former governor of Massachusetts, claims for himself.

While still untested, Perry is said to have cross-over appeal among Republican voters -- from social conservatives and the small government Tea Party to the mainstream business element -- that Romney lacks.

A Perry candidacy could be the first major test of Romney's 2012 bid, forcing the former venture capitalist to compete within his party and to engage on controversial issues that he has often dodged.

"Mitt Romney is running with blinders on. Perry could force him to pivot. Should all things go right for him, Rick Perry is Romney's biggest threat," said Republican strategist Ford O'Connell, chairman of the CivicForum PAC.

Democrats and some Republicans have rapped Romney for acting as if he is already his party's pick, and behaving as if he does not need to campaign heavily or to stake out his policy positions.

Last week in Los Angeles, Romney was asked about criticism from some of his fellow Republicans. He declined to be drawn into intraparty squabbles, saying that he was campaigning against Obama. In Virginia on Monday, he raised eyebrows by reportedly musing at a fund-raiser about who might be on his short-list for a running mate.

Polls have shown Romney ahead of rival Republicans. But his support has mostly been low at under 30 percent.

In fact, many see an enthusiasm gap for Romney, with Republicans keen for a more dynamic alternative with stronger conservative credentials.

He is distrusted by some conservatives for his role in creating a universal healthcare program in Massachusetts that became the model for Obama's 2010 national healthcare reform.

Perry's pugnacious style -- he told a New Hampshire newspaper this week that he "loves the give and take and the personal engagement" -- could be appealing to Republicans keen to take over the White House.

"Perry is a fighter, and a lot of people want to be enthusiastic about someone -- not just an Obama alternative," said O'Connell. "Perry is the best campaigner we have."

Above all, Perry's arrival would force Romney to campaign against his peers, not just against Obama.

"Man-to-man combat is not Romney's preferred game mode, whereas Perry will not hesitate to take it right to him," said Jeffrey Berry, professor of political science at Tufts University in Medford, Massachusetts.

ATTRACTIVE ENTRY POINT

A Gallup poll this week showed Romney at 27 percent support among announced Republican candidates. But if Perry were to run, he would start within five percentage points of Romney.

Romney's campaign might contrast its candidate's private-sector experience with Perry's many years in Texas government.

"Overall, I don't think Romney has a lot of strong points to make against Perry," said Berry. "If I was in the Romney camp, I would be worried sick.

Romney's second bid for the White House has been marked by staying above the fray. Campaign materials have been strictly on-message about the economy and jobs.

"President Obama said if he didn't turn around the economy in three years, he would be looking at a one-term proposition. He's right," Romney said in a statement ahead of a campaign stop in Pataskala, Ohio, on Wednesday.

And yet on the most troubling issue facing the country, the debt ceiling problem, the lack of leadership from Romney suggests he wants to avoid stepping into a political minefield that could blow up in his face in a general election.

After Monday night's dueling televised statements from Obama and House Speaker John Boehner on the approaching debt ceiling deadline, Romney responded with a single Twitter post, criticizing Obama.

If Perry runs, what some call the "Texas jobs miracle" of recent years will likely be contrasted with Romney's weaker record on job creation in Massachusetts.

The Federal Reserve Bank of Dallas estimates that Texas accounted for between 29 percent and 43 percent of total U.S. employment gains from June 2009 through May 2011.

"Name recognition is still an issue for Perry, but when you can just keep touting that jobs record, the name recognition will follow," said O'Connell.

By contrast, during Romney's term, Massachusetts ranked 47th among the 50 U.S. states for job creation.

While running the buyout firm Bain Capital in the 1980s and 1990s, Romney oversaw big layoffs at some of the businesses the firm invested in.

But Bain also helped build businesses such as big-box retailers Staples and Sports Authority, creating thousands of jobs.