BOSTON, Aug. 1 - Gov. Mitt Romney says he will decide in the next few months whether to run for the Republican presidential nomination. And if he does, his résumé will carry him a long way. He is the high-profile governor of a prominent state. He has a background as a turnaround specialist in the business world and as the savior of the scandal-plagued 2002 Olympics in Salt Lake City. He is telegenic and articulate, and he is wealthy.
But as Mr. Romney tries to appeal to his conservative party, his biggest nemesis may end up being the moderate image he created for himself in getting elected in Massachusetts, possibly the bluest state in America, where only 14 percent of the voters are registered Republicans.
"I think it's a question that people may ask at some point," John Campbell III, a Republican state senator in California, said after Mr. Romney spoke to Orange County Republicans in June. "How did this guy get so many Democrats in Massachusetts to support him?"
That is something that many people are asking, especially after last week, when Mr. Romney took conservative positions on two controversial subjects - abortion and the morning-after pill - that appeared to contradict the more moderate stances he had made in his campaign for governor in 2002 and before.
Mr. Romney's actions come as two other potential Republican presidential candidates, Gov. George E. Pataki of New York and Senator Bill Frist of Tennessee, are also making carefully calibrated decisions on volatile social issues.
Last week, Mr. Frist defied President Bush and many conservative supporters by supporting a bill to increase federal financing for embryonic stem cell research. And this week aides to Mr. Pataki announced that he would veto legislation making the so-called morning-after pill available without a prescription.
Mr. Romney vetoed a similar morning-after bill, but he went much further than Mr. Pataki, who supports abortion rights. Mr. Romney labeled the morning-after drug an "abortion pill" - not just emergency contraception, as the Food and Drug Administration calls it - and wrote an opinion article for The Boston Globe saying that he did not believe that abortion should be legal.
Mr. Romney, who in the past had said that abortion should be "safe and legal" and that he supported the "substance" of the Supreme Court decision legalizing abortion, wrote in the article that his views on abortion had "evolved and deepened."
His actions stirred dismay among some moderate Republicans and prompted predictions that he would seek national office. They also underscored the challenge that Mr. Romney is likely to face in primaries where conservative voters often hold the upper hand.
"Within the Republican Party, the nominating process, Massachusetts has been kind of the liberal state that the conservative Republicans like to point at," said Paul Cellucci, a former Republican governor of Massachusetts who until recently was President Bush's ambassador to Canada. "That kind of becomes something he has to overcome."
In recent months, Mr. Romney has appeared to be trying to do just that by emphasizing conservative positions on combustible social issues like gay marriage, stem cell research and the death penalty. As he has traveled to strategic states like South Carolina and Iowa, he has portrayed himself as a conservative fish swimming upstream in Massachusetts, or, using a metaphor with more macho appeal, as "a cattle rancher at a vegetarian convention."
Mr. Romney said he vetoed the morning-after pill legislation because the pill could in some cases prevent a fertilized egg from implanting in the uterus. Although the veto was symbolic - the Democratic-controlled legislature is certain to override it - Mr. Romney's actions angered many of those who supported him for governor in 2002 on the belief that he was more moderate.
"It's not our style to oppose any Republican candidate, but we're calling Mitt on this," said Jennifer Blei Stockman, national co-chairwoman of the Republican Majority for Choice. Ms. Stockman said that Mr. Romney sought the group's endorsement in 2002 and received it only after making the case that he supported keeping abortion legal.
"We feel very betrayed," she said, but added, "If it weren't for the waffling on these issues, he probably would make a good president."
Although some conservatives welcomed Mr. Romney's actions last week, others were skeptical.