Romney even traveled to Lancaster, Pa., on Thursday to campaign for McCain, who has wrapped up the nomination and faces no serious threat in the state's April 22 primary.
"I think it is important for him to be the president, because I think he would do the critical things that have to be done, and they are reform our entitlement system, rein in government spending, rid our dependence of foreign oil, improve our education system so that our kids really can compete globally," Romney told Fox News last month.
Once bitter rivals, Romney now says any Republican would be honored to be McCain's running mate, and he included himself.
Would he be a good vice presidential candidate? Romney sidestepped the question at Thursday's event. "Right now, I am focusing on getting Senator McCain the support he needs to win this election" he said. "He's got a lot of great people he can consider for the second spot."
Is Romney being scrutinized by McCain's campaign? "You'll have to direct that somewhere else," he said.
Romney made millions as a venture capitalist and clearly can count. McCain is 71 and, if he wins, would be the oldest president elected. As vice president, Romney would be in an ideal spot if McCain decides against a second term. If McCain goes the distance, the preternaturally youthful Romney would be 69 in 2016.
And if a Democrat wins in November, Romney appears certain to challenge the incumbent in four years.
Since quitting the GOP race Feb. 7, Romney has tried to preserve his political base, maintaining contact with his supporters and financial backers. He is looking at creating a political action committee so he can travel and make donations to like-minded Republican candidates. And Romney has given strong consideration to a foundation that would promote conservative ideals.
"We've talked about the creation of a new entity that would allow the governor to remain politically active past this election year," said Eric Fehrnstrom, who served as Romney's press secretary and is one of a handful of aides still on his payroll.
Questioned about another bid, Fehrnstrom said, "It's too early to predict what the future will hold."
In his first run for national office, Romney emerged as a tough challenger to McCain, raising more than the senator while spending $47 million of his own money. He garnered 294 delegates in a sometimes bitter campaign. McCain often railed against Romney's thin foreign policy credentials while Romney made an issue of McCain's admission that economics was not his strong suit.
At an event Thursday challenging McCain and his record, Democratic Party Chairman Howard Dean offered a backhanded compliment of Romney.
"You know, frankly, Mitt Romney was the candidate I feared the most" in the general election as the Republican nominee, Dean said. "Because he's got money, he's wealthy. He's very articulate and willing to say practically anything."
New Jersey state Sen. Joseph Kyrillos, who served as Romney's New Jersey campaign chairman, said he has received four thank-you phone messages from Romney, which is more telling than the buttoned-down persona of the campaign.
"I think people thought they knew John McCain and Rudy Giuliani, but they didn't have a full sense of who was Mitt Romney. I'm not sure why; I just know from my point of view the translation wasn't made. But that's ultimately to his benefit, because that is still to come," Kyrillos said.
Romney endorsed McCain a week after dropping out of the race. Last month, they jointly attended fundraisers in Utah and Colorado, two Mountain West states the GOP is counting on this fall.
Romney's support for McCain has been most evident in fundraising. One of his national finance co-chairs, former eBay CEO Meg Whitman, is now serving the same role for McCain. Another former Romney finance co-chair, L.E. Simmons, is arranging a major fundraiser for McCain in Houston on May 10.
Yet a day earlier, Romney will take advantage of the McCain event to meet with former backers in Houston. The Beach Boys will provide musical entertainment.
Eric Tanenblatt, Romney's Georgia state and national finance co-chairman, said some attendees at a recent fundraiser he helped arrange for McCain approached him and raised the prospect of the two former rivals uniting on a ticket.
"They'd love to see that," Tanenblatt said. "In the South, Republicans are conservatives, and he's a conservative that a lot of people rallied around."
Not all conservatives.
The specter of Romney joining a McCain ticket prompted some to launch an anti-Romney petition at www.NoMittVP.com, as well as to place full-page ads in newspapers where McCain is campaigning. The ads question Romney's commitment to conservative ideals and have been supported by Paul Weyrich of the Free Congress Foundation, who had endorsed Romney.
"If Governor Romney is on your ticket, many social conservative voters will consider their values repudiated by the Republican Party and will either stay away from the polls this November or only vote down ticket," the ad tells McCain.
Instead, they talk about former Arkansas Gov. Mike Huckabee, who won the Iowa caucuses before his campaign faded, or a pair of governors: Jon Huntsman Jr. of Utah or Mark Sanford of South Carolina. Other potential running mates include Minnesota Gov. Tim Pawlenty and Rob Portman, a former Ohio congressman who headed the White House Office of Management and Budget.
Romney and his aides brush off the conservative criticism. Instead, they press on, which included a guest slot for Romney providing news and comment on Paul Harvey's nationally syndicated radio show.
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