Romney leads the polls in Iowa, although Huckabee is gaining ground. If Romney wins the Hawkeye State, observers say he is likely to win New Hampshire easily, where he has a strong advantage due to serving as governor in neighboring Massachusetts.

Wins in Iowa and New Hampshire would give Romney big momentum heading into the Jan. 15 primary in Michigan, where he has raised large sums of money and enjoys prominence because his father served as governor.

Giuliani, who leads the field in national polls, could have a difficult time reversing Romney in South Carolina, where conservatives dominate and the former mayor’s positions on guns and abortion could pose problems, say political strategists.

Florida is different because Republican primary voters are much more ideologically diverse than in earlier primary states.

“There is a tremendous amount of Midwestern and Northeastern influence here. It’s a very diverse state in its population mix,” said former Gov. Bob Martinez, a Giuliani campaign adviser.

Giuliani is not the only candidate relying on Florida as a firewall. So is Thompson, whose conservative credentials play well in northern section of the state and in the panhandle, which resembles southern Alabama politically.