2012 Decoded

Florida Sen. Marco Rubio, a Republican superstar expected to top the vice presidential shortlist, on Wednesday said Mitt Romney has "earned'' the Republican nomination for president and called a potential floor fight at the convention a "recipe for disaster.''

In an interview with Fox News host Sean Hannity, Rubio didn't name Romney rivals Rick Santorum and Newt Gingrich but said it was clear they would not be able to win enough delegates to lock down the nomination before the Republican convention.

"I think we're at a stage now where at least two of the candidates have openly admitted that the only way they're going to be able to win the nomination is to have a floor fight in Tampa in August. I don't think there's anything good about that,'' he said. He added, "It's increasingly clear that Mitt Romney will be the Republican nominee.''

Pressed by Hannity whether he was in fact offering his endorsement, Rubio said yes. But he offered something even better -- the rising figure in the conservative and tea party movements vouched for Romney's conservative credentials.

"I have zero doubt in my mind of two things,'' Rubio said. "No. 1 that Mitt Romney will govern as a conservative. No. 2, he will be head and shoulders better than the guy who is in the White House right now.''

Expect to see those words sooner rather than later in a television ad.

Rubio has said he had no plans to endorse a candidate almost as firmly as he has insisted he won't be a vice presidential contender. He repeated that Wednesday night saying, "That's not what I want to be and that's not what's going to happen.''