The story so far

Previously: Republican U.S. Reps. Paul Broun, Phil Gingrey and Jack Kingston have said they are running for Saxby Chambliss' Senate seat.

The latest: Democrat U.S. Rep. John Barrow said he will not seek the seat.

What's next: Other candidates are considering whether to run.

For months, many Georgia Democrats have believed their best shot at taking an open U.S. Senate seat was Rep. John Barrow, the battle-tested campaign veteran who has the conservative profile that could have given him a statewide shot.

But Barrow ended months of speculation Tuesday when he announced he would not compete next year for the seat held by U.S. Sen. Saxby Chambliss. The decision sent Democrats scrambling anew to find a contender for the coveted seat.

“I’m grateful for the encouragement I’ve received from folks all across the state of Georgia, but I’ve decided that I will not be a candidate for the Senate in 2014,” Barrow said in a statement. “I enjoy my work on behalf of the folks in the 12th District, and I look forward to continuing to serve them in the House of Representatives.”

» WHO'S RUNNING: Republican U.S. Reps. Paul Broun, Phil Gingrey and Jack Kingston

» WHO'S NOT RUNNING: Democratic U.S. Rep. John Barrow

» WHO'S WORTH WATCHING: Michelle Nunn, CEO, Points of Light; State Rep. Scott Holcomb (D-Atlanta); former Georgia Secretary of State Karen Handel; businessman David Perdue and businesswoman Kelly Loeffler

The five-term congressman, the sole white House Democrat from the Deep South, has time and again survived tough election odds in his southeast Georgia district and is expected to face another fight to keep his seat in 2014. But Georgia’s conservative electorate and the prospect of a contested primary no doubt loomed large.

Barrow’s decision opens the door for Michelle Nunn, the daughter of former senator Sam Nunn and head of the volunteer service organization Points of Light. She didn’t return a call seeking comment, but supporters had urged her to run regardless of Barrow’s decision. Her refusal to step aside – setting up a potentially contentious primary — was a factor in Barrow deciding not to run.

Former Atlanta Mayor Shirley Franklin, a Nunn booster, said Barrow was “too conservative” because of his voting record. Among other things, Barrow voted against the 2010 Affordable Care Act, also known as Obamacare.

Franklin said Nunn has “an excellent reputation among women — and not just among liberals. I know people are writing it up as liberals.”

Franklin said Nunn has proven she can raise money and her father can provide inroads into Georgia’s conservative Democrats.

“The question is: Does she want it,” Franklin said.

Other Democrats have eyed a run, including state Rep. Scott Holcomb of Atlanta. He wouldn’t comment on the possibility but said he’s confident a “strong Democratic candidate will emerge.”

As Democrats work to come up with a consensus candidate, the growing Republican field is shaping up to become a race to the right. Republican U.S. Reps. Paul Broun, Phil Gingrey and Jack Kingston have announced they will run, and former Georgia Secretary of State Karen Handel, businessman David Perdue and businesswoman Kelly Loeffler  are said to be weighing bids of their own.

Georgia Democratic Party chairman Mike Berlon said Barrow’s decision will help consolidate the field and allow Democrats to focus on the next steps. He said Washington Democrats are now talking to Michelle Nunn about her potential bid.

“John is in a situation where he’s probably the only guy who can win that congressional seat back, and we’ll need that for the next cycle,” said Berlon. “From the party’s perspective this solves one part of the equation. Now we can move forward and go for a non-contested or barely-contested primary.”

Barrow is perennially targeted by national Republicans and can expect another contested race in the 12th District in 2014. But if he had not run for his House seat again, it would have almost certainly been a GOP pickup, given the electorate’s Republican-leaning makeup.

Republican groups, meanwhile, welcomed the news that a well-known candidate opted out of a run. The National Republican Senatorial Committee crowed that Barrow’s decision will make it much easier for Republicans to hold the seat next year.

“This is the biggest recruiting failure of the 2014 cycle,” said NRSC spokesman Brad Dayspring. “Democrats in Washington threw everything at him, so it’s quite an embarrassing failure for Barrow to leave the [party] at the altar. Republicans have a strong field of candidates that represent Georgia values and will win in 2014.”