McCain emerged as the front-runner in the Republican race with a victory in the winner-take-all primary in Florida last Tuesday. In the days since, he has begun collecting endorsements from establishment figures ranging from California Gov. Arnold Schwarzenegger to former Sen. Don Nickles of Oklahoma.
But a significant number of conservatives remain vocally opposed to him, and Romney hopes to take advantage of their unwillingness to swing behind a longtime party maverick.
"It's going to destroy the Republican Party," radio show host Rush Limbaugh has said of a McCain nomination. Ann Coulter, the conservative author and commentator, has said she would prefer Clinton in the White House over McCain, adding, "I will campaign for her."
Complicating Romney's challenge is the continuing presence of Huckabee. As long as the Baptist minister is running, Romney strategists concede the two men will split the votes of conservatives who are not ready to back McCain.
"I believe that the majority of Republican Party conservatives are convinced that I'm best equipped to lead this country, unify our party and take on the challenge of radical Islamic extremism," McCain told reporters.