U.S. House budget chair Paul Ryan endorsed Mitt Romney Friday morning, making him one of the most high-profile Republicans to back the former Massachusetts governor for the GOP nomination.

Ryan, a Republican from Wisconsin and leading voice for the GOP on fiscal issues, told the Milwaukee-Wisconsin Journal Sentinel that the unusually long Republican race is getting to the point where it's going to become counter-productive if the primary drags on.

It's going to get much tougher to defeat Barack Obama in the fall, said Ryan.

Ryan is yet another strong endorsement Romney can add to a list of surrogates that include Marco Rubio, R-Fla., former Florida Gov. Jeb Bush, R-Fla., and New Jersey Gov. Chris Christie. He is also rumored to be on the vice presidential short list.

Ryan: Romney Has Earned The Nomination

Ryan's statement echoed that of Rubio's and Bush's, which just came in within the past two weeks, and called for Republicans to unite behind the front-runner so that they can move on to focusing on winning in the general election. Both Rubio and Ryan said Romney has earned the nomination.

I think he deserves to be the nominee. I think he earned it. He has emerged as the best candidate, Ryan told the paper.

He added on Fox News: It's clear to me he understands the fork in the road America is facing.

Romney has supported Ryan's controversial budget plan, which passed the GOP-majority House Thursday. Although the $3.5 trillion plan, which promises to transform Medicare and cut spending by $5.3 trillion over the next 10 years, is doomed to die in the Democrat-back senate, the House vote (largely along party lines) was a symbolic move to show what Republicans would do if that had more control.

The Journal Sentinel reportd Ryan will be campaigning with Romney in Wisconsin, which will hold its primary on Tuesday.