Gerald Herbert, Associated Press
Sen. John McCain, left, shakes hands with Mitt Romney in Boston, where the former rival endorsed McCain's presidential bid.

WASHINGTON — Now that Mitt Romney has endorsed Sen. John McCain, his former rival for the GOP presidential nomination, does that mean there will be a role for him in a McCain administration?

Romney quit the race for the White House a week ago, but on Thursday released his delegates and endorsed the Arizona senator at a news conference in Boston with McCain by his side.

The chances of the newfound unity between the once fierce rivals translating into a McCain-Romney ticket, though, seemed like a long shot to political observers. More likely, they say, might be a Cabinet-level appointment.

Or Romney could have set aside his differences with McCain to boost his standing in the Republican Party in anticipation of making another run at the White House. That could come as soon as 2012 if McCain loses in November.

"I'm not sure — and indeed doubt — anything concrete was offered for this endorsement," said Kirk Jowers, director of the University of Utah's Hinckley Institute of Politics and a longtime Romney supporter.

But, Jowers said, Romney clearly stands to benefit by coming forward now, especially with former Arkansas Sen. Mike Huckabee staying in the race even though it's all but impossible at this point for him to amass enough delegates.

"It certainly makes every possibility, from vice president to the Cabinet to greater support in a future run, much more likely," Jowers said. "He is unquestionably a front-runner for 2012 if a Democrat wins in 2008."

Matthew Wilson, a religion and politics professor at Southern Methodist University in Texas, said a Cabinet post such as Commerce secretary might be more likely than vice president.

Or, Wilson said, at least a good speaking slot at September's Republican National Convention.

Herb London, president of the Hudson Institute, a neoconservative think tank headquartered in Washington, D.C., said McCain, 71, is going to need someone full of "youthful vitality" as well as conservative and Southern as a vice presidential candidate.

"I don't see what Romney could bring to the ticket. He could deliver Utah, but what difference would that make?" London said. "Utah would go for the Republican anyway."

But Charles W. Dunn, dean of Regent University's School of Government, said

the endorsement was "make-up time" and that Romney would be a good running mate.<

"Delivering your home state is just one of a number of criteria," Dunn said. "Solidifying the conservative base is more important than the electoral vote (of Massachusetts)."

He agreed that McCain does need to penetrate the South but solidifying the conservative base would help bring the South.

"McCain desperately needs to mend fences with the conservative base and Romney could play a significant role there," Dunn said. "Romney has the hard-core conservative support." Dunn said evangelicals also trust Romney more than McCain and that would help bring in votes as well.

Utah pollster Dan Jones said Romney's endorsement of McCain will help make the Arizona senator more attractive to the state's voters. Jones found in a poll taken last week after Romney dropped out that nearly as many Utahns favored voting for a Democrat, Illinois Sen. Barack Obama, as for McCain.

Even without Romney on the ticket, McCain can still win GOP-dominated Utah in November, Jones said, but shouldn't expect a 90 percent victory like Romney enjoyed in the Feb. 8 primary. "He could walk across the Great Salt Lake and not do that," Jones said.

Jeffrey Berry, a political science professor at Tufts University in Boston, said Romney might not want to be McCain's pick. Especially given the tough time Republicans may have winning in November.

"I don't think this is the beginning of a 'Romney for Vice President' movement," Berry said. "If Romney comes to the conclusion that McCain is going to lose, he might not want to be on the ticket."

Republican consultant David E. Johnson, the CEO of Strategic Vision, said there's an obvious reason why Romney won't be McCain's pick for the nation's No. 2 spot — the "animosity between the two."

"Mitt Romney would jump at the chance, and it would help McCain with conservative voters," Johnson said, but there are issues between them that "run very deep and very personal."

But at the press conference, Romney and McCain took the focus off their often-tense relationship and instead looked to how their teaming up will help Republicans beat the eventual Democratic nominee.

"Even when the contest was close and our disagreements were debated, the caliber of the man was apparent," Romney said. He described how he and McCain shared laughs at debates.

"I recognize it is time for us to put aside our differences and focus on the places where we think we have common ground," Romney said. "Right now, the Democrats are fighting, let us come together and make progress while they're fighting."

Obama and Sen. Hillary Clinton of New York are locked in an increasingly tight battle for the Democratic nomination.

"Gov. Romney will help me draw the stark differences that exist between myself and the things that he and I stand for and believe in, and the Democratic candidates," McCain said. "I look forward to his continued very important role of leadership in our party that he has exercised in the past and will exercise even more so in the future."

The move is another step in the quickly changing election landscape. In Florida, Romney and McCain attacked each other's records before the Jan. 29 primary, which McCain ultimately won.

After McCain picked up significantly more delegates on Feb. 5th's Super Tuesday, Romney promised he was in the race until the Republican National Convention. But following a day of closed-door meetings with his staff and family members, Romney called it quits.