Top Republican officials are closing ranks behind Rep. Jack Kingston's Senate bid.

Rep. Phil Gingrey, the fourth-place finisher in last month's crowded GOP primary, is set to endorse the Savannah Republican on Wednesday, two people with direct knowledge of the decision said. It's not immediately clear what role he'll play ahead of the July 22 runoff between Kingston and businessman David Perdue.

Kingston's campaign is trying to parlay a unique accord between establishment forces, such as the U.S. Chamber of Commerce, and outsider elements on the GOP's right flank. He has picked up the blessing of former Georgia Secretary of State Karen Handel, who finished in third place with the help of tea party support, as well as the backing of most of Georgia's congressional delegation.

Kingston's campaign declined to comment but said it would hold a "major political announcement" on Wednesday morning. Gingrey, who has represented a northwest Atlanta district for more than a decade, could help Kingston make inroads to vote-rich metro Atlanta. Gingrey won four counties in northwest Georgia, and he and Handel helped dampen Perdue's lead across the northern part of the state.

For Perdue's camp, getting spurned by elected officials could play into his message of being an outsider set on shaking up the Washington status quo. He's long run on his business credentials and his campaign has argued that rank-and-file Republicans will make up their minds on who to support on their own.

Perdue also has establishment support of his own, including the backing of his first cousin, former Gov. Sonny Perdue.

Kingston and Perdue have both courted Rep. Paul Broun, the tea party favorite who finished fifth. It's not immediately clear whether he'll endorse either candidate, though we're told Kingston's camp has had recent discussions with the Athens Republican. Also on the sidelines are most other prominent Republicans, including Gov. Nathan Deal.