Mitt Romney plans to endorse John McCain Thursday. (Photo Credit: AP)
(CNN) - Former Massachusetts Gov. Mitt Romney is expected to endorse U.S. Sen. John McCain of Arizona, who was Romney's rival in the Republican race for the White House, two sources familiar with the decision told CNN Thursday.
They said Romney wants the 286 delegates he won to go to McCain, who now has 827 delegates, and is the Republican front-runner.
To clinch the Republican nomination 1,191 are needed.
An announcement is expected at 3:30 p.m. ET in Boston.
Romney dropped out of the race Feb. 7, after a poor showing on Super Tuesday. He said he pulled the plug on his Republican presidential campaign "for our party and for our country."
Continuing his campaign would have delayed the Republicans from shifting attention to the general election campaign against whichever Democrat wins the nomination of their party, he said at the time.
Programming note: Watch Larry King’s exclusive interview with GOP front-runner John McCain tonight on Larry King Live at 9 P.M. Eastern.
– CNN's Dana Bash contributed to this report