ATLANTA – Dueling endorsements from Sarah Palin and Newt Gingrich could help decide a crowded Republican primary for Georgia governor Tuesday. Palin's nod to former Secretary of State Karen Handel has helped her surge to the top of the polls in recent days, while ex-congressman Nathan Deal could benefit from the backing of Gingrich. The two served together in the U.S. House.

On the Democratic side, one-term former Gov. Roy Barnes is facing the first electoral test in his comeback bid. Barnes was ousted in 2002 by Republican Sonny Perdue, his defeat fueled by teachers angry with his education reforms and others upset over his successful push to remove the Confederate battle symbol from the state's flag.

Seven Democrats and seven Republicans are vying for the open seat. Perdue is prevented by term limits from running again after two terms.

Palin's endorsement of Handel — the lone woman in the race who could become the state's first female governor — swiftly helped change the dynamic. Handel had been attacked throughout the campaign as too liberal. Palin's backing — she called the former secretary of state a "pro-life, pro-Constitutionalist with a can-do attitude" — was seen as a conservative seal of approval. Handel had the lead in a new poll released Sunday.

Handel is just one of several candidates around the country recently endorsed by Palin, John McCain's running mate during the 2008 presidential campaign. Palin is largely credited with helping South Carolina Rep. Nikki Haley, once little-known in her state, surge to popularity and ultimately a runoff win for the GOP nomination for governor.

The day after Palin posted her Handel endorsement on Facebook and Twitter, Gingrich threw his support behind Deal.

State Insurance Commissioner John Oxendine is also in the running for the GOP nod and has been the Republican money leader throughout the campaign.

The Republican race is widely expected to head to an Aug. 10 runoff, which would be required if none of the candidates wins more than 50 percent of the vote.

Barnes is the front-runner in the Democratic contest. His most formidable challenger is Attorney General Thurbert Baker, who has the backing of former President Bill Clinton and is seeking to become Georgia's first black governor.

Barnes announced last spring that he would make another bid for the governor's mansion. He ran a folksy but focused primary campaign attacking ruling Republicans in the state for neglecting big problems, like education and transportation, amid the crippling recession.

Georgia voters will also select a Democrat to run against Republican U.S. Sen. Johnny Isakson, who doesn't have a GOP opponent in his bid for a second term and has $5 million on hand for his campaign.

In north Georgia, Republican U.S. Rep. Tom Graves could face yet another runoff after winning a special election runoff in June for the seat once held by Deal. Deal left Congress to run for governor, and now Graves is seeking a full two-year term.

His leading opponent is former state Sen. Lee Hawkins, whom he defeated in June's runoff. There are five Republicans in the race, which could make a runoff necessary.

Elsewhere, three Democratic congressmen are facing opposition in the primary — U.S. Reps. Hank Johnson, David Scott and John Barrow.

Eight GOP contenders are vying to replace Republican Rep. John Linder, who is retiring after nine terms.