The Upshot says that GOP chances for taking control of the Senate are rising primarily because the party is increasingly likely to hold onto Georgia.
“With these developments, our rating in Georgia has steadily progressed from Tossup to Lean Republican to Likely Republican, and now gives Michelle Nunn only a 12 percent chance to win in November. For several months, Georgia had represented a possible window of opportunity for Democrats in a midterm cycle in which most Democrats are playing defense. Although Ms. Nunn cannot yet be counted out, this latest polling suggests that window may be closing.”