Romney, who lost a bitter fight against McCain for the GOP nod, withdrew his candidacy last week, saying it was for the good of the party to unite behind the front-runner. He echoed that thought on Thursday with McCain standing to his side.
"As all of you saw over the past year, things can get pretty rough in a political campaign and in the thick of the fight it's easy to lose sight of your opponent's finer qualities," Romney said. "But the truth of the matter is in the case of Sen. McCain, I could never quite do that. Even when the contest was close, and our disagreements were debated, the caliber of the man was apparent."
Though the duo hit each other hard on the campaign trail, they played good friends during a quick appearance at Romney's soon-to-be-defunct headquarters. McCain, the target of several attack ads by Romney, praised his former opponent for a "hard, intensive, fine, honorable" campaign.
"It is also extremely important to me that not only do I have his endorsement but that we join together now and travel this country, not only on behalf of my candidacy" but all other GOP candidates for House, Senate and governor's offices and beyond, McCain said.
Romney's move frees up all 286 of his delegates won in primaries across the United States, including the 36 he won during Utah's Feb. 5 primary, where he stomped all competitors by taking 90 percent of the GOP vote.
The process for what happens to those delegates, however, is unclear because party rules do not address the course of the bound delegates when a candidate drops out, says Utah GOP Chairman Stan Lockhart.
"We're going where no man has gone before," Lockhart said. "Our rules don't really say one way or another."
Lockhart says the party's Central Committee will be consulted on what happens with the delegates, but that ultimately the party will follow Romney's instructions because the delegates are his.
"As a party we're going to want to do whatever Gov. Romney wants us to do," Lockhart said.
Not everyone, though, is falling in line with McCain.
Rep. Chris Cannon, R-Utah, said this week he will back the eventual nominee of the party, but McCain still has much work to do.
"Whoever the nominee is will need an energized conservative base to win in November, and I hope he will do what is necessary to create that energy," Cannon said this week.
Former Arkansas Gov. Mike Huckabee, who has vowed to continue his candidacy despite long and almost insurmountable odds, told CNN that there was a lot of "me too" going on in the Republican Party to get behind McCain.
"But there's still a lot of Republicans around this country who have yet to vote," Huckabee said. "Many of whom feel their voice is still needing to be heard."
Romney aired scathing television commercials about McCain during the GOP race and at one point labeled the senator a "liberal." Romney constantly slammed legislation McCain had sponsored and his press shop churned out daily e-mails pointing out McCain's flaws, one of which was called the "Straight Talk Detour," a take off McCain's Straight Talk Express bus tour.
Conversely, McCain had no qualms about calling Romney a flip-flopper and questioned his pandering to different audiences. The enmity between the two camps often boiled over. Romney stepped aside on Feb. 7, saying it was better for the party to end the contentious battle and unify its efforts. But his endorsement of McCain brought guffaws from the other side of the aisle.
John Walsh, chairman of the Massachusetts Democratic Party, noted that only last week Romney was telling America that McCain was the wrong choice for president.
"Mitt and McCain are both emblematic of exactly what's wrong with Washington: Politicians who will say or do anything to get elected," Walsh said. "Voters weren't fooled by Gov. Romney, and they won't be fooled by Sen. McCain in November."