ATLANTA — A rare open US Senate seat in Georgia promises a scrambled 2014 campaign that already has some Republicans quietly nervous about retaining it.
Democrat Barack Obama lost the state in both of his White House races, and it is a seat that Republicans cannot afford to lose as they try to regain a Senate majority for the final two years of his presidency.
The question is whether a bruising party primary becomes a liability, particularly if voters nominate US Representative Paul Broun, who once called evolution and the Big Bang Theory ‘‘lies straight from the pit of hell.’’
Broun and US Representative Phil Gingrey, both conservative doctors, are the only Republicans to announce officially since incumbent Saxby Chambliss said he will retire. But the GOP primary field eventually could include as many as a half-dozen candidates with a credible shot at a runoff spot.
Broun drew national headlines last year for that science commentary he delivered at a church. He has flouted GOP leaders on recent fiscal votes.
In a fund-raising letter, he said that he was the first member of Congress to call Obama ‘‘a socialist who embraces Marxist-Leninist policies.’’
That makes Broun a Tea Party favorite. To other Republicans, however, such comments stir memories of 2012 losses in Senate races in Missouri and Indiana where the Republican nominees, Todd Akin and Richard Mourdock, made controversial comments on women, rape, and abortion.
‘‘There’s no question that the Republican Party in Georgia and the nation are concerned that we could have another Todd Akin-type scenario here,’’ said Heath Garrett, a GOP campaign consultant and former top aide to US Senator Johnny Isakson.
Democrats control 55 Senate seats, and Republicans need to hang on to the ones they control now and pick up six more next year to take control.
At least one more Georgia congressman is expected to jump in, and a trio of Washington outsiders is considering the race: a wealthy Atlanta businesswoman who helped bankroll Mitt Romney’s presidential campaign; a former Susan G. Komen Foundation executive who took on Planned Parenthood; and the cousin of former Governor Sonny Perdue.
‘‘It’s going to be a free-for-all with a lot of dominoes,’’ said Sue Everhart, state GOP chief.
Isakson said he is neutral in the primary.
National conservative groups FreedomWorks and Club for Growth, which have helped Tea Party candidates such as Senator Ted Cruz of Texas win high-profile races, say many candidates have talked to them about support.
For now, both groups say they are watching the field develop. It would be a blow to Broun if he cannot harness the support of either.
Democrats think they can tap the Missouri-Indiana playbook, particularly if US Representative John Barrow, a moderate from Augusta, runs. Barrow has survived consecutive elections as one of national Republicans’ top House targets.
The state Democratic chief, Mike Berlon, said Barrow has detractors among core Democrats for his vote against Obama’s health care law, but said he would expect enthusiasm at any opportunity to win back Chambliss’ seat.