While Sethi has the backing of Paul, Texas’ Sen. Ted Cruz and former Sen. Jim DeMint of South Carolina — a trio who frequently battled party leaders in Senate races during the Obama years — Hagerty has the support of Trump and Sens. Marsha Blackburn of Tennessee and Tom Cotton of Arkansas.

GOP sources said Paul’s tactics have annoyed Tennessee Republicans, particularly Blackburn. In an ad running in the state, Paul, staring into the camera, says: “Tennessee is too conservative a state to keep sending Democrats in Republican clothing to represent Tennessee.”

The ad angered Blackburn, multiple sources said. When asked if she thought Paul’s and Cruz’s efforts in the state were helpful, Blackburn replied, “Probably not.”

Tennessee’s Republican Sen. Lamar Alexander, whose retirement has sparked the primary fight, told CNN that Paul’s ad “basically says Tennesseans need to stop electing Democrats dressed as Republicans. So, I don’t wear a dress … and my voting record in support of Trump is 90% and his is 69%.”