Isakson, 69, is in his second term. He was first elected to the House in 1999 to replace former Speaker Newt Gingrich (R-Ga.). His formal announcement will come less than two weeks after Election Day, when Republican David Perdue won the seat of retiring Sen. Saxby Chambliss (R-Ga.).
Georgia Democrats were initially buoyed by the candidacy of Michelle Nunn, which resulted in weeks of public polling suggesting the race was close and might be forced into a runoff, though it resulted in an eventual 8-point loss to Perdue. Nunn and State Sen. Jason Carter, who lost in his bid to unseat Deal, would be seen as early frontrunners to challenge Isakson.