(CNN) -- Add Al Gore to the list of big-name surrogates who are making campaign cameos in the last remaining Senate election this year. The former vice president will team up with Jim Martin at a campaign event Sunday in Atlanta, Georgia.
Martin is a former Georgia state lawmaker who is the Democratic challenger to Saxby Chambliss, Georgia's freshman Republican senator, who's fighting to keep his seat. The two candidates face off in a runoff election December 2.
Chambliss won a plurality of the vote on Election Day, but Georgia state law calls for the winner to grab at least 50 percent plus one vote. Because of the inclusion of a third-party candidate, Chambliss fell just shy of that threshold, forcing a runoff.
Gore's campaign appearance follows that of former President Bill Clinton, who teamed up with Martin on Wednesday in Atlanta.
President-elect Barack Obama is lending his voice to the Democrats' efforts to win back the Republican-held senate seat in Georgia. Obama speaks out in a 60-second radio ad for Martin that hit the airwaves Friday.
A trio of former Republican presidential candidates have campaigned for Chambliss. Arizona Sen. John McCain returned to the trail with Chambliss just nine days after losing the presidential election to Obama.
Last week, former Arkansas Gov. Mike Huckabee, who ran for the Republican presidential nomination before dropping out in March and backing McCain, campaigned with Chambliss.
And on Friday, former Massachusetts Gov. Mitt Romney teamed up with Chambliss in Atlanta and Savannah. Like Huckabee, Romney also ran for the GOP presidential nomination before ending his bid in February and backing McCain. Both men could make another stab at presidential politics in 2012.
Do these big-name surrogates make a difference?
"Generally, they can help boost turnout because of all the media attention. Turnout in a runoff election is often very low compared to a presidential election, and each side needs to get as many of their voters to the polls as possible," CNN senior political analyst Bill Schneider said.
Democrats have so far picked up seven Senate seats in this year's election, with the Republican seats in Georgia and Minnesota still undecided. In Minnesota, freshman GOP Sen. Norm Coleman topped his Democratic challenger, Al Franken, by just 215 votes, triggering an automatic recount that will extend into December.
If the Democrats take both remaining contests, they'll reach their pre-election goal of controlling 60 Senate seats, which would be a filibuster-proof majority. A filibuster is a move by the minority party in the Senate that basically brings the chamber to a standstill by blocking votes on legislation.