Think tank president Gary Palmer defeated state Rep. Paul DeMarco in the Republican runoff for retiring Rep. Spencer BachusSpencer Thomas BachusTrump bank nominee gets rough reception at confirmation hearing Overnight Finance: Breaking - GOP delays release of tax bill | Changes to 401(k)s, state and local taxes hold up bill | Trump aims to sign tax legislation by Christmas | Hensarling to retire after term | Trump to repeal arbitration rule Senators, don't put Ex-Im Bank's fossil fuel financing back in business MORE's (R-Ala) seat on Tuesday night.

Palmer took 62 percent support to DeMarco's 38 percent support when The Associated Press called the race, with half of precincts reporting.

His success marks a total reversal in fortune for a candidate who wasn't the favorite ahead of the initial round of primary voting. And it gives the Club for Growth a win in a cycle when the conservative group has had a mixed rate of success in races up and down the ballot.

While the Club initially endorsed surgeon Chad Mathis in the primary, it shifted its support to Palmer after he took second in the first round of voting.

The group dropped more than $250,000 into the race on ads attacking DeMarco as supporting tax increases during his time in the legislature. That gave Palmer room to build a positive personal narrative, touting himself as the family values, policy-oriented candidate in the race.

“Congratulations to Gary Palmer, a smart conservative who will fight the big government liberals in Washington at every turn,” Club for Growth President Chris Chocola said in a statement after Palmer's win. “Gary will stand for limited government and individual liberty, and he’ll do everything possible to repeal ObamaCare. Alabama conservatives have made a great choice in taxpayer hero Gary Palmer and the Club’s PAC was happy to support him in the Republican runoff election.”

Palmer also nabbed the support of a handful of big-name conservatives, including former Pennsylvania Sen. Rick Santorum (R) and Indiana Gov. Mike Pence.

DeMarco never managed to recover from initial missteps in the runoff. He launched an early attack ad using a decade-old quote of Palmer's to allege the candidate once supported tax increases that was widely panned by local media as being taken out of context.

Palmer now has an easy path to a November win in this deep-red district.