UPDATED 6:32 p.m. | Rep. Connie Mack IV, the frontrunner for the Republican nomination for Senate in Florida, shored up his conservative credentials today with the endorsement of tea-party-affiliated conservative Sen. Mike Lee (R-Utah).

Mack, who has picked up endorsements ranging from Republican White House candidate Mitt Romney to conservative Kentucky Sen. Rand Paul (R-Ky.), is the favorite to beat former Sen. George LeMieux in the Aug. 14 primary.

“Connie Mack’s fight to protect our constitutional freedoms and cut the size and scope of the federal government has been a hallmark of his service to the people of Florida,” Lee said in a statement released by the Mack campaign. “Having Connie’s voice in the U.S. Senate will greatly enhance our ability to not only stop Harry Reid and Bill Nelson’s liberal agenda, but to return our nation to a path of constitutionally limited government, more individual liberty, and greater prosperity.”

The winner of the GOP primary will face an uphill climb against two-term Sen. Bill Nelson, who is widely expected to outperform President Barack Obama in November.

In a recent interview, Senate Minority Leader Mitch McConnell (R-Ky.) put Florida in the least competitive tier of races where the GOP could make a pickup this cycle, alongside Pennsylvania.

Roll Call rates the Florida Senate race as Leans Democratic.