State Rep. Joe Carr, a conservative Republican who has been running against embattled Rep. Scott DesJarlais, R-Tenn., announced Tuesday that he will switch gears to challenge Sen. Lamar Alexander, R-Tenn., instead.

Carr is the first Republican to announce a primary challenge to Alexander, who has received fierce backlash from some tea party groups for his work with his Democratic colleagues.

Local tea party activists are currently vetting other potential Alexander challengers — a process they say will begin this month. Other potential GOP primary challengers include Knox County Mayor Tim Burchett and former Williamson County Chairman Kevin Kookogey, according to the Tennessean.

Until Tuesday morning, Carr was running in the Republican primary against DesJarlais and state Sen. Jim Tracy.

Unseating Alexander will be an uphill battle for Carr, who enters the primary with a severe disadvantage on the fundraising front. Carr had $275,000 in cash on hand at the end of the second quarter, compared with Alexander’s $3.1 million.

Carr had trouble raising a significant amount of money in his primary challenge to DesJarlais. The congressman has been dogged by revelations stemming from a past divorce proceeding that alleges he had affairs with patients and co-workers and he coerced his wife and a former mistress into having abortions.

Tracy outraised Carr and DesJarlais by hundreds of thousands of dollars in the second quarter.

The Tennessee Senate race is rated a Safe Republican contest by Rothenberg Political Report/Roll Call.