Sarah Palin endorsed underdog state Rep. Joe Carr (R) against Sen. Lamar Alexander (R-Tenn.) Wednesday, lauding Carr's hard-line stance on immigration.

"He’s stood up to those in his own party, fighting to enact some of the toughest illegal immigration legislation in the country and working to make Tennessee the 4th most business friendly state in the nation," Palin wrote in a statement on her Facebook page.

Palin thanked Alexander for his many years of service. But she added, "Unfortunately, advocating and voting for amnesty, cash for clunkers, bailouts, raising the debt ceiling, and many controversial Obama administration nominees has marred the incumbent’s record. It’s time for a change."

Carr is running to Alexander's right, mainly on immigration. Influential national conservative groups have not embraced his candidacy, however. Organizations like the Club for Growth and Senate Conservatives Fund, both known for backing insurgent challengers against senators, have stayed out of the Tennessee race.

Most observers regard Alexander as the clear front-runner ahead of the Aug. 7 primary, which also includes some lesser-known candidates.

Carr is trying to make a late push with the help of national conservative surrogates. He campaigned with conservative radio host Laura Ingraham on Tuesday.