The Dec. 2 runoff is a daunting challenge for resurgent Georgia Democrats eager to win back the seat they lost in 2002 - and a key litmus test for the state's dominant Republican base to flex its muscle.
They'll have their work cut out for them. Voters seem tired of heading to the polls - which they will have done three times in the past five months.
"I'm tired of hearing about the election," said Kevin Curtis, a 40-year-old in Atlanta. "It's just too much publicity. I want it to be done with. I just want everyone to do their job, to stop talking about it and just start working."
Chambliss, a first-term senator who ousted Max Cleland six years ago, is urging his supporters to vote by mail and hosting mega-rallies with once (and perhaps future) GOP presidential candidates.
Martin's campaign is focusing its efforts on get-out-the-vote drives energized by the help of about 100 aides to Barack Obama's campaign. And it is also encouraging voters to head to the polls early; advance voting in many counties begins next week.
Both campaigns are playing vigorously to their bases, knowing that turnout could fall well short of the roughly 4 million who cast ballots last week. The turnout for the last statewide Senate runoff, a 1992 victory by Republican Paul Coverdell, dropped by roughly 1 million votes.
"If you could simply get back the people who voted for you the first time, you'd win in a landslide," said Charles Bullock, a University of Georgia political science professor. "So it comes down to who has a better ground game."
The Chambliss camp has organized rallies and hosted high-profile speakers in GOP strongholds. Sen. John McCain made his first political appearance since losing the presidential race on Thursday in Cobb County, urging voters "to go into battle one more time."
Former Arkansas Gov. Mike Huckabee, who carried Georgia in the Feb. 5 presidential primary, will headline an event in the vote-rich Atlanta suburb of Gwinnett County on Sunday. And the Chambliss campaign has invited Alaska Gov. Sarah Palin, the GOP's vice presidential nominee, to come to town.
The campaign said they're trying to stir up excitement to appeal to voters wary of politics after the long presidential campaign.
"We want to keep our supporters engaged, to let them know that our voters are still engaged," said Michelle Hitt Grasso, a Chambliss spokeswoman. "And part of it is keeping the profile high - letting them know we're not quite done yet."
The Republican National Committee, recognizing they're battling voter-fatigue, sent out fliers to prospective voters appealing to their sense of duty when most probably just want to get ready for the upcoming holiday season.
The fliers contain two applications for a vote-by-mail ballot and a note from Georgia's Republican Gov. Sonny Perdue: "I know many of us are ready to put politics aside and enjoy spending time with our loved ones. But stakes are high."
The Democrats don't have the benefit of a powerful presence in red-state Georgia. And the party's standard-bearer, President-elect Barack Obama has been busy with his transition to the White House.
The Martin campaign has reached out to Obama to headline an event, but his aides suggested it didn't need party honchos to mobilize its supporters. Instead, it is banking on help from Obama's veteran field operatives to help increase turnout.
They will spread the message that Martin is "focused on what we have to do now to work with our next president," said spokesman Matt Canter.
"Jim Martin's message about working with Barack Obama to fix the economy will mobilize turnout," he said. "As people learn, not just Barack Obama supporters want someone who is going to work with our next president."
There's a lot at stake in the runoff's results. Democrats are looking for a filibuster-proof margin in the Democratic-controlled Senate.
Senate Democrats have 55 seats and two independents who caucus with the party, and races in Alaska and Minnesota also have yet to be called. A Martin victory would help Democrats get one step closer to a 60-seat Senate majority they need to block GOP filibusters.
The mild-mannered Martin seems like an unlikely prospect to lead a Democratic resurgence in Georgia, particularly after he was trounced in the low-profile race for lieutenant governor by a GOP unknown just two years ago.
But he's been helped by a surge of Obama voters and a wave of anti-incumbent frustration. Some conservatives also abandoned Chambliss in the wake of his vote for the $700 billion bailout bill, and it's unclear how those factors will play out.
Chambliss faces the runoff because he failed to cross the 50 percent threshold required by Georgia law. He earned 49.8 percent of the vote to Martin's 46.8 percent. Libertarian Allen Buckley siphoned off 3.4 percent.
For Democrats, who once had a tight grip on Georgia politics, it's a chance to prove the party is a potent force in the state without Obama on the ballot, political analysts say.
"It's the first test of what will become a major test in 2010: Can you mobilize these people who got excited about Obama when he's not on the ticket?" asked Bullock. "Can you transfer his charisma to somebody else?"