Former Massachusetts Gov. Mitt Romney will endorse Marco Rubio over Gov. Charlie Crist in Florida's Republican Senate primary more than two years after Crist helped crush Romney's presidential aspirations by endorsing rival John McCain.
Romney plans to announce the endorsement Saturday and campaign with Rubio in Tampa on Monday, according to a Romney adviser who asked to remain anonymous because the official announcement has not been made.
Romney is the third major 2008 presidential candidate to endorse Rubio. Former New York Mayor Rudy Giuliani and former Arkansas Gov. Mike Huckabee have also endorsed the former House speaker. Giuliani, who endorsed earlier this month, was also counting on a Florida victory during the 2008 campaign and now says Crist backed out of a promised endorsement.
Crist and Rubio both sought Romney's endorsement, the adviser said, but Romney believes Rubio has a stronger conservative record and is an idea-driven leader. Romney was also disappointed that Crist vetoed a teacher merit-pay bill this week that was a high priority for Republican lawmakers and former Gov. Jeb Bush.
Romney's PAC is contributing the maximum $5,000 allowed to Rubio's campaign. In 2006, Romney flew to Tallahassee as head of the Republican Governors Association with a $1 million check to help Crist's run for governor.
In 2008, Romney and McCain were in a tight battle for Florida with Romney slightly ahead in polls leading up to the primary. Crist endorsed McCain just three days ahead of the election and some political observers believe it was enough to give McCain the win, which he used to build momentum and capture the nomination.
Romney is often mentioned as a potential 2012 presidential candidate. By backing Rubio, a favorite of conservatives, Romney could endear himself to Republican voters who were uncomfortable with his moderate stands on abortion and gay rights when he ran for office in Massachusetts.
The Rubio campaign said it would not comment on the endorsement until after it's made. The Crist campaign didn't immediately respond to e-mails seeking comment.
Crist was considered the favorite when both entered the race last May, but Rubio has risen from obscurity to front-runner status with a message opposing President Barack Obama's agenda. He frequently reminds voters that Crist hugged Obama at a Fort Myers rally in support of the $787 billion federal stimulus package that Congress later passed.
A Quinnipiac poll released this week showed Rubio 23 points ahead of Crist in the primary.
Crist, who has upset many conservatives with a more moderate approach to governing, is rumored to be considering a run as an independent candidate. He has until April 30 to decide. Florida's primary is Aug. 24 and Crist wouldn't be able to get on the November ballot as an independent if he loses.
U.S. Rep. Kendrick Meek is the leading Democrat seeking the seat held by Sen. George LeMieux, whom Crist appointed to fill Mel Martinez's unexpired term.