ATLANTA (AP) - Voters are making their picks across Georgia in what could be the biggest test yet for Newt Gingrich as he fights to keep his bid alive for the Republican presidential nomination.

Gingrich was favored to win in Georgia on Tuesday, but his rivals spent time and resources in the state, hoping to grab a share of the state's 76 delegates. Opponents were also hoping to deal Gingrich a humiliating defeat in the state he represented in Congress for 20 years. The polls were open from 7 a.m. until 7 p.m.

The former House Speaker didn't take any chances in Georgia. He spent the days leading up to Tuesday's contest campaigning in Georgia rather than logging time in the other nine states holding Super Tuesday contests. A loss in Georgia, Gingrich told voters at campaign stops, could cripple his White House hopes.

Mitt Romney and Rick Santorum both campaigned in Atlanta's suburbs and sent surrogates to appeal to GOP groups across the state.

Lena Sisselman, 96, said she was voting for Romney.

"I think he is the only one who can beat Obama," she said outside a polling place in the Buckhead area of Atlanta. "I think Gingrich is a smart man, but he's out of place."

Not so long ago, the Gingrich camp viewed Georgia as a lock. But Santorum's victories last month in Minnesota, Missouri and Colorado, and Romney's wins in Arizona and Michigan, have turned Georgia into a must-win for Gingrich.

A victory in Georgia on Tuesday and a strong showing in Tennessee, Oklahoma and Ohio could position him well for next week's contests in Mississippi and Alabama, two states with Republican voters similar to Georgia's.

Gingrich, who now lives in suburban Virginia, had a slew of advantages heading into the primary. He was backed by establishment support built on decades of relationships in Georgia, where many GOP figures still view him with an almost reverential vibe for his role in building up the party. He also had the endorsements of state Republican heavyweights, including Gov. Nathan Deal and former presidential candidate Herman Cain.

Gingrich played up his local ties whenever given the chance. He made stops last week at the University of West Georgia, where he taught geography and history during the 1970s, and the Capitol, where supporters wore buttons identifying themselves as members of "Newt's Army." He also played to Georgia voters' concerns over rising fuel prices, vowing that his energy plan would reduce gas to $2.50 a gallon.

But the state's population jumped more than 18 percent since Gingrich last held office in the late 1990s, a flood of residents who may have little memory of his time in government. Some voters who do remember are unconvinced that he's the best choice for president.

"I was living here when he was in Congress, and I just don't think he's a good candidate," said Vanita Knight, a 66-year-old registered nurse who was voting Tuesday morning in Atlanta.

"I just didn't see him accomplishing much in Congress," Knight said. "He seemed full of hot air."

Meanwhile, Santorum made a play for the social conservative vote across the state, and Romney's camp hoped to build on a base of support that earned him 30 percent of the vote in the 2008 Republican presidential primary won by former Arkansas Gov. Mike Huckabee.

Other states holding Super Tuesday contests were Alaska, Idaho, Ohio, Oklahoma, Massachusetts, North Dakota, Tennessee, Vermont and Virginia.