Conservative activist Gary Palmer defeated state Rep. Paul DeMarco Tuesday to win the GOP nomination in Alabama's 6th District.
Palmer defeated DeMarco, 62 percent to 38 percent, with 50 percent of precincts reporting, according to The Associated Press.
GOP operatives say DeMarco's loss is partly a result of the Club for Growth's barrage of spending in the final weeks of the runoff. The GOP nominee will almost certainly succeed Rep. Spencer Bachus, R-Ala., who is retiring from this conservative district.
In the June 3 GOP primary, DeMarco came in first in a seven-candidate field with 33 percent — below the 50 percent threshold to avoid a runoff in the Yellowhammer State. Palmer trailed in second place with 20 percent.
But after the runoff, the club endorsed Palmer and spent more than $250,000 in television ads attacking DeMarco's record on taxes.
The attacks, along with some other missteps from DeMarco's campaign , boosted Palmer in the polls. About a week out, GOP operatives said Palmer looked to be cruising to an easy victory on Tuesday.
GOP presidential nominee Mitt Romney won the district in 2012 with 74 percent, making it one of the strongest Republican districts in the country.
The seat is open for the first time since 1992.