Both parties have brought their big guns to this usually reliably-Republican southern state ahead of the Dec. 2 run-off election.
Former President Bill Clinton was in Atlanta Tuesday stumping for the Democratic challenger while failed Republican presidential candidate John McCain and former Arkansas Gov. Mike Huckabee, who tried for the Republican presidential nomination, have campaigned for the incumbent.
"The hopes of America are riding with Georgia," Clinton told a crowd of about 2,000 at a chilly outdoor rally.
If Democrats can pick up the Georgia seat as well as a contested seat from Minnesota, they will control the 60 votes in the 100-member Senate needed to overcome the minority's procedural hurdles. While setting that milestone for the first time in 30 years, it would not guarantee success of Democrats' bills as senators may cross party lines.
The Senate race in Georgia went to a run-off because incumbent Republican Saxby Chambliss narrowly failed to reach the required 50 percent threshold over Democrat Jim Martin.
In Minnesota, results of the contest between Republican incumbent Norm Coleman and Democratic challenger Al Franken are headed to a recount next month.
Turnout in early voting in Georgia is sharply lower than for the Nov. 4 contest in which Democrat Barack Obama was elected the country's first black president but failed to carry Georgia.
"The person who wins this (run-off) election will be the one whose supporters want it the most .... You just have to decide how much you want it," Clinton told the rally at Clark Atlanta University, which has a history of serving African American students.
Jennifer Duffy, who tracks Senate races for the nonpartisan Cook Political Report, said the Georgia contest appears close with the Republican incumbent clinging to a small lead.
"I put a thumb on the scale for Chambliss .... A lot favors Chambliss ... but Democrats may have a shot," Duffy said, adding that the race could turn, in part, on whether President-elect Obama goes to Georgia to campaign.
"If he goes down there, it's a sign it's very, very close and potentially winnable for them (Democrats)," Duffy said.
The president-elect would not put his political reputation on the line to campaign in Georgia unless Martin's chances looked good, said political science professor Merle Black, of Emory University in Atlanta.
Obama has not said whether he will campaign in the state.
National Issues
Republican candidates have held an advantage in Georgia, which sits in a belt of southeastern states that are among the country's most conservative.
But in the presidential race Obama upset political calculations by bringing to the polls a larger number of black voters who were motivated in part at the prospect of electing the country's first black president.
Black voters overwhelmingly choose Democrats, and their votes helped Martin overcome the disadvantage he faced in a state where Republicans usually do better at getting voters to the polls, said Charles Bullock, political science professor at the University of Georgia in Athens.
"Obama was able to offset that (Republican advantage) but the challenge for Democrats is: 'can you remobilize those voters when you don't have your star at the top of the ticket,"' Bullock said.
Some Republican voters are disenchanted with Chambliss because of his support for an immigration reform bill in 2007 and a vote for a massive bailout of Wall Street firms in October.
But Chambliss has presented himself as a "firewall" against a potential Democratic agenda run amok, which would resonate with voters wary of that prospect, Bullock said.
Chambliss infuriated Democrats in his campaign in 2002 against incumbent Max Cleland, who lost three limbs during the Vietnam war. During that race Chambliss questioned Cleland's patriotism.
