Florida Sen. Marco Rubio endorsed Mitt Romney Wednesday evening, as Republicans look to close out a long GOP primary that some worry is damaging the eventual nominee’s odds against the president in 2012.

“It’s evidently and increasingly clear that Mitt Romney’s going to be the Republican nominee,” Mr. Rubio said in a Fox News interview with Sean Hannity. (Fox is owned by News Corp., which also owns The Wall Street Journal). He then offered up an official endorsement for Mr. Romney.

“Marco Rubio is living proof that the American Dream is still very much alive,” Mr. Romney said in a statement circulated by the campaign. “Senator Rubio’s endorsement is a major milestone in my effort to make Barack Obama a one-term president. Ann joins me in thanking him for the confidence he is placing in my leadership and for the great honor he has done me today.”

In a sign of lingering worries among the GOP, Mr. Rubio warned that a fight to the convention would further harm Republicans.

“There is no way that anyone can convince me that having a floor fight at the convention in Tampa in August is a recipe for victory in November,” Mr. Rubio said. “On the contrary, I think it’s a recipe for disaster.”