GOP Sen. Tom Coburn (Okla.) endorsed Mitt Romney for president on Sunday, praising him as the candidate "best equipped to solve the urgent problems before us."
In a letter published in The Oklahoman newspaper, Coburn praised Romney as a "leader."
"Washington tends to be divided between two groups — leaders and career politicians," wrote Coburn. "Leaders tend to have a wealth of real-world experience outside of politics and are in office to give rather than take something from their position. Career politicians, on the other hand, mean well but are ill-equipped to solve problems. Their greatest skill is getting re-elected.
The endorsement of Coburn, a solid fiscal conservative, should boost Romney a day ahead of the pivotal Super Tuesday primaries.
Oklahoma is one of 10 states voting on March 6, with some 419 delegates up for grabs in all contests. Alaska, Idaho, Tennessee, Georgia, Ohio, Massachusetts, North Dakota, Vermont and Virginia will also vote on Super Tuesday.
The senator also took a shot at Romney's rivals in the GOP field.
"[H]aving served with the other candidates, I do know something about the field. Each candidate has admirable qualities. However, on too many occasions I have seen each behave like career politicians rather than leaders," he wrote.
Coburn has served in Congress with former House Speaker Newt Gingrich, former Sen. Rick Santorum (Pa.) and Texas Rep. Ron Paul.
Coburn is known to have a strong personal relationship with President Obama. In his endorsement of Romney, Coburn criticized the president, saying he had "campaigned as a transformational leader, yet he has rejected transformational solutions."
Romney, the presumptive nominee, has failed to put away his GOP challengers, who have sought to position themselves as the conservative alternative to the former Massachusetts governor.
Polls show the biggest Super Tuesday prize, Ohio, as too close to call. Last week, Santorum led in polls there, but surveys released over the weekend showed him in a virtual dead heat with a surging Romney.