Points of Light CEO Michelle Nunn speaks in 2011. (Kevin Wolf/AP)

Michelle Nunn just raised the stakes in Georgia’s Republican primary for U.S. Senate.

In announcing a Senate campaign that had been expected for weeks, the Democrat with a well-known last name gave her party a credible contender capable of making it a competitive general election, particularly if Republicans squander the advantages with which they begin the race.

Nunn is the latest entrant into a complex national battle for control of the Senate. Republicans are expected to have to net six seats next year to win the majority. Georgia and Kentucky represent the only two realistic pickup opportunities for Democrats, though both contests look like long shots for the party. But if Democrats can steal away even one of those two seats, it would make it awfully difficult for Republicans to take control of the chamber.

And that’s where Nunn, 46, comes in. The head of a nonprofit group that promotes volunteerism, she is the daughter of former senator Sam Nunn, a centrist Democrat who represented the Peach State in the upper chamber for nearly a quarter-century. The younger Nunn is a political newcomer in a state that Republicans have dominated in recent years.

“I’m running for Senate because I believe that America’s spirit of innovation and entrepreneurship, when unleashed, can create extraordinary possibilities,” Nunn said in a Tuesday e-mail to supporters. “We need to tap into the creativity of citizens and businesses to create jobs and a better future.”

The Republican side of the race to replace retiring Republican Sen. Saxby Chambliss is shaping up as a competitive contest. The field includes Reps. Paul C. Broun, Jack Kingston and Phil Gingrey and former Georgia secretary of state Karen Handel.

Broun, in particular, could pose problems for Republicans in the general election. Controversial comments and strident conservatism could make him a shaky GOP nominee. Meanwhile, Gingrey has stoked controversy with a remark that former Senate nominee Todd Akin of Missouri was “partly right” about rape. Gingrey later said that his remark was misconstrued and argued that he was not defending Akin’s comments about “legitimate rape” rarely causing pregnancy.

On the heels of a 2012 cycle in which controversial candidates Akin and Richard Mourdock in Indiana cost Republicans seats in red states, Republicans in Georgia are under extra pressure to nominate an electable contender.

“I don’t think Nunn is ready for prime time, but Republicans must still be responsible and nominate a well-funded, reasonable candidate,” said Joel Mc­Elhannon, a GOP strategist unaligned with any of the Senate candidates. “It is now very important that Georgia Republicans have a nominee who represents the best values of the Republican Party and has the resources for a tough runoff and general-election campaign.”

Democrats are already trying to stir the pot in the GOP primary, believing that if the contest produces a flawed nominee, Nunn would be well positioned to pounce. In a fundraising e-mail for the Democrat circulated Tuesday, Sen. Kirsten Gillibrand (D-N.Y.) declared that “the alternative is disturbing.”

Nunn’s allies are hoping that her nonpolitical background and her well-known last name will boost her ability to build a moderate statewide profile. Unlike her father, who cut his political teeth at a young age in the state legislature, Nunn hasn’t waded deeply into politics before now.

She is the chief executive of Points of Light, a group that encourages volunteerism. The organization formed out of the 2007 merger of the HandsOn Network, a group that Nunn headed, and the Points of Light Foundation, which was formed in 1990 in response to President George H.W. Bush’s call for Americans to volunteer.

Nunn flirted with a Senate bid in 2004, but she said she declined so she could focus on her family. A Phi Beta Kappa graduate of the University of Virginia, Nunn has studied overseas at Oxford University and in India.

Republicans, meanwhile, are going after Nunn. They note that a conservative Democrat, Rep. John Barrow, declined to run, and they have sought to tie Nunn to President Obama and Democratic congressional leaders, noting that she was at a Democratic Senatorial Campaign Committee fundraiser with Obama in May. The National Republican Senatorial Committee has begun decrying the “Obama/Nunn agenda.” Given Georgia’s red tilt, it could be a long campaign for the first-time candidate.

Demographic trends have given Georgia Democrats an extra reason to be hopeful about their competitiveness in statewide elections. A surge in the number of minority residents, who typically favor Democrats, has stoked optimism in the party about turning Georgia blue or at least purple in the coming years. But with Republicans controlling all statewide offices, Democrats have a long way to go, observers say. And 2014 may be too early to see any major shift.