The antitax Club for Growth on Thursday waded into two Republican runoffs for U.S. House in Georgia, endorsing Barry Loudermilk and Bob Johnson in a pair of conservative-leaning districts.

Loudermilk, a tea party-backed state senator, was the top vote-getter in the 11th district Republican primary on Tuesday. He faces former congressman Bob Barr, who was on the front lines of the effort to impeach President Bill Clinton and was the Libertarian nominee for president in 2008.

The winner of the July 22 runoff will be a heavy favorite to win in the general election because of the district's conservative tilt. Mitt Romney won nearly 67 percent of the vote there in 2012. Rep. Phil Gingrey (R) vacated the seat to run for U.S. Senate.

Johnson, a physician, faces state Rep. Buddy Carter, who is competing with him for the GOP nomination in the district vacated by Rep. Jack Kingston (R). Kingston is in a GOP runoff for U.S. Senate.

Romney won nearly 56 percent of the vote in Kingston's 1s district.