Now the big question of his viability arises

If Governor Mitt Romney's announcement yesterday answers the biggest question in Massachusetts politics, it raises an even bigger one: Is he a viable presidential candidate?

The short answer is yes, according to political analysts, observers, and Republican activists across the country. But the longer answer, they say, is that Romney faces tough challenges: convincing Southern conservatives that he's not a Northeast liberal, becoming conversant in foreign policy, and overcoming prejudices against his religion.

''Yes, he is a viable candidate: He's got a spectacular reputation in Republican circles, the camera loves him, and he's got a very focused message," said former Republican National Committee chairman Rich Bond.

But, Bond added, ''He's got a lot of work to do."

With the first primaries more than two years away, other possible candidates -- including US Senator John McCain, former New York mayor Rudolph Giuliani, and a half dozen others -- have significantly more name recognition and political experience than the one-term Republican governor of Massachusetts. His highest-profile legislative goal, passing a healthcare bill, remains unfinished, with Democrats in the Legislature still negotiating a compromise.

Yet, by all accounts, Romney has turned himself into a top prospect for 2008 with a busy out-of-state schedule in 2005 and by taking increasingly conservative positions on gay marriage, abortion, and the environment in recent months. He will get more chances to grow his political network as chairman of the Republican Governors Association in 2006.

Romney isn't likely to announce a presidential bid for another year, and the headlines in 2006 could have a big impact on his plans. If the war on terror continues to dominate, McCain, one of the country's leading voices on defense, could have an edge. On the other hand, if the economic threat posed by China is a defining story, Romney could do well.

Several observers say that Romney has a legitimate shot at capturing the nomination if he can finish in the top three in Iowa, win or take second in New Hampshire, and woo enough conservatives to make a stronger showing in South Carolina than McCain.

''Romney has the potential to put together a serious run for the nomination," said Scott Reed, who ran Bob Dole's presidential campaign in 1996.

In Iowa, Romney has left a strong impression on voters, activists, and politicians on the trips he has taken, including a quick jaunt last Saturday for two fund-raisers. One was for Brad Zaun, a Des Moines state senator who said he was impressed by Romney's down-to-earth manner.

''Even though he's been very successful, he comes across as a very humble, genuine person," said former Iowa governor Terry E. Branstad, one of several leading Iowa Republicans who held a private meeting with Romney during his visit. ''And, yeah, I think that will have appeal in Iowa."

One possible drawback for Romney, Branstad said, might be that some Iowa caucus members would be hesitant to vote for a Mormon politician. Branstad said he urged Romney at their meeting to put his family -- Romney is married with five sons -- front and center to show he's a family man with traditional values.

Bond, who considers Romney a ''tier two" candidate for now, said the governor ought to study how George H.W. Bush instantly became a top-tier candidate in 1980 by beating Ronald Reagan in the Iowa caucus.

As for New Hampshire, Romney is in an enviable position. He owns a vacation home in Wolfeboro, has made several political trips to the state, knows the Republican operatives, and enjoys heavy media coverage because of the proximity to Boston.

The chairman of the Republican Party in New Hampshire, Warren Henderson, said that part of Romney's strength is that he has a mastery of both policy and personality, unlike many politicians. Romney, he said, ''clearly can do both."

But Romney's proximity to New Hampshire also ups the stakes for him there; a loss would be a major setback. McCain, who beat President Bush in the New Hampshire primary in 2000, could again emerge as the top pick if he runs.

Despite the hype about Romney in New Hampshire, some say it's way too early to handicap his prospects there.

''I guess I would say we've got to see more of him to get a really good grip of what he believes," said Jean White, a former state senator in New Hampshire and longtime activist in Republican politics.

Of all the early primary states, South Carolina would perhaps be Romney's biggest test.

Rick Beltram, chairman of the Spartanburg County Republican Party, said the governor has been very well-received in his trip there, but he said that coming from Massachusetts could be a liability. Beltram said that when he first brought up Romney's name to party activists, their response was this: ''How can we possibly have somebody from Massachusetts? They're all liberals."

Beltram said Romney must appeal to financially and socially conservative voters in Spartanburg and other key counties.

''There's no reason to think that Mitt Romney would not be a very viable candidate," he said.

Mike Green, a Republican activist and founder of the political website SC Hotline, isn't so sure. Romney may not be sufficiently conservative, he said, and voters are instead more likely to favor another probable candidate, Virginia Senator George Allen.

Though Romney calls himself ''prolife" and a firm abortion rights opponent, his views on abortion have shifted to the right over the last decade. He pledged during his 1994 Senate race against Senator Edward M. Kennedy to keep abortion ''safe and legal in this country," which could cause conservatives not to fully trust him now.

''I just don't see how Mitt Romney is going to catch fire down here," Green said of voters in South Carolina.

Romney, who continues to build a political network, has pockets of support across the country: in Michigan, where he grew up and where his father, George Romney, was governor; in Utah, where he successfully ran the 2002 Winter Olympics; and in California, where he has traveled and enjoys relationships with donors, particularly in the Republican bastion of Orange County.

Scott Helman can be reached at shelman@globe.com.