ABC News' George Stephanopoulos and John Berman Report: Former Gov. Mitt Romney, R-Mass., today endorsed his former Republican rival Sen. John McCain, R-Ariz. The endorsement took place this afternoon at Romney for President headquarters in Boston.
Romney asked his delegates to throw their support to McCain, the presumptive Republican presidential nominee.
"Even when the contest was close and our disagreements were debated, the caliber of the man was apparent," Romney said, standing with McCain for the announcement at his now-defunct campaign's headquarters in Boston. "As a party, we come together."
Accepting Romney's endorsement, McCain said despite a "hard campaign" now "we move forward together for the good of our party and the nation."
Once bitter rivals locked in an acrimonious Republican nomination fight, Romney abandoned his 2008 bid following a poor showing in the Super Tuesday contests this month. Romney had won the support of many in the conservative wing of the party, but failed to overtake McCain in either delegates or the number of state wins.
The former governor made his decision to endorse today in the interest of helping McCain gain the 1,191 delegates he needs to secure the party nomination and unite the party for the general election against the Democrats in November.
Romney campaign manager Beth Myers notified McCain campaign manager Rick Davis in a telephone call today of Romney's decision, and they immediately made arrangements for an announcement in Boston this afternoon since McCain was campaigning in Rhode Island today.
After McCain's townhall meeting near Providence this afternoon, the campaign is flying to Boston for the endorsement.
Romney and McCain will meet today before they both announce the formal endorsement at a press conference.
ABC News' Ron Claiborne and Bret Hovell contributed reporting.