Republican campaign dropout Mitt Romney endorsed John McCain for the party's presidential nomination and asked his national convention delegates to swing behind the likely nominee.
"Even when the contest was close and our disagreements were debated, the caliber of the man was apparent," the former Massachusetts governor said, standing alongside his one-time rival at his now-defunct campaign's headquarters.
Romney collected 280 delegates during his run through the early primaries and caucuses, enough to move McCain close to the total of 1,191 needed to clinch the nomination a full nine months before the November general election.
The officials who disclosed Romney's plans did so on condition of anonymity to avoid pre-empting a formal announcement later in the day. McCain was campaigning in Vermont and Rhode Island, and added a flight to Boston to appear with Romney to accept the endorsement at his waterfront campaign headquarters.
McCain effectively sealed the nomination last week when Romney withdrew from the race; only former Arkansas Gov. Mike Huckabee and libertarian-leaning Texas Rep. Ron Paul remain. Both lag McCain in delegates to the Republican nominating convention this summer.
Romney's nod of support capped a bitter yearlong rivalry between the two men over the party's nomination. Romney criticized McCain in television ads in New Hampshire, and both candidates targeted each other almost daily during campaign events and debates. Neither is especially fond of the other.
Over the past year, Romney cast McCain as outside of the Republican conservative mainstream and a Washington insider who contributed to the problems plaguing a broken system. McCain, in turn, argued that Romney's equivocations and reversals on several issues indicated a willingness to change his positions to fit his political goals.
The clash effectively ended on Feb. 5, when McCain won a string of big-state "Super Tuesday" primaries from coast to coast.
Officials said the former Massachusetts governor made his decision to back McCain earlier in the day, citing a desire to help the Arizona senator wrap up the nomination before too much more time passed and while Democrats still did not have a nominee.
McCain is on a steady march toward amassing the 1,191 delegates he needs, but Huckabee has proven an unexpectedly durable challenger. With a strong appeal to evangelical conservatives, Huckabee defeated McCain in two out of three states that chose delegates last weekend, and ran a far stronger race than expected before losing the Virginia primary on Tuesday.
The senator began the day with 843 delegates, to 242 for Huckabee.
While Romney can ask his delegates to support McCain, he will not be able to simply hand over all 280 delegates. Many are from caucus states that will not select the actual delegates until state conventions this spring. Those delegates will be selected by people who supported Romney in the initial caucuses; the direction they go depends on whether they follow Romney's lead in endorsing McCain.
In other states, the delegates are bound to Romney, and their fate is governed by state party rules. In states like Montana, where Romney has 25 delegates, they would be free to support whomever they choose after Romney releases them.
Six of Romney's delegates are members of the Republican National Committee who continued to endorse him even after he dropped out of the race. These RNC members are free to support any candidate they choose at the convention, and not all of them appeared eager to endorse McCain,
"I will support our nominee," RNC member Diane Adams of Indiana said simply.
Other Romney supporters like Stewart Iverson in Iowa said they will work to rally others behind McCain.
"My main focus is to try to bring Republicans together and say, he may not have been our choice in the caucuses but he is where we are today," Iverson said Wednesday.
In the next round of voting, Louisiana holds a state convention Saturday in which caucus-goers will help decide how 44 of the state's 47 national convention delegates are split. At stake Tuesday in Wisconsin's primary are 40 Republican delegates.
A former Massachusetts governor, Romney suspended his candidacy last week after it became apparent that toppling McCain would be near impossible to gain the delegates needed to defeat McCain.
In a speech before conservative activists in Washington, D.C., Romney acknowledged the difficulty in overtaking McCain. "I must now stand aside, for our party and our country," he said at the time, adding that doing otherwise would increase the chances that Democrats would reclaim the White House.
At the time, Romney did not offer an endorsement, and McCain said he did not seek one when the two spoke by telephone.
Romney was the only one of McCain's main primary opponents who had resisted lining up behind the nominee in waiting; former New York City mayor Rudy Giuliani and former politician and actor Fred Thompson both have endorsed him.