Facebook/Michelle Nunn

Democratic candidate Michelle Nunn could be poised for an upset win in the Georgia Senate race — or perhaps, to push the entire election season into a special overtime round.

In a new poll from CNN, Nunn has 47 percent support, ahead of Republican nominee David Perdue with 44 percent, plus 5 percent for Libertarian candidate Amanda Swafford. The survey of likely voters was conducted from Oct. 19 to 22, and has a margin of error of plus or minus 4 percentage points.

The seat is currently held by Republican Sen. Saxby Chambliss, who is retiring after two terms.

Under Georgia law, if no candidate is able to get at least 50 percent of the vote, the state will hold a special runoff election — which would be held two months later, on Jan. 6.

Thus, it's possible that even after new members of Congress are sworn in on Jan. 3, control of the Senate itself might still be up in the air until Georgia voters head to the polls again.