According to Real Clear Politics' average of the key polls, just three weeks out from the midterms, Republicans safely hold 50 Senate seats and Democrats safely hold 44 seats. That means for Democrats to gain the coveted 51-seat majority, they have to win all six of the "toss-up" seats and somehow manage to win over one of the Republicans' "safe" seats, which is looking increasingly unlikely.
One of the toss-up seats is in Nevada, where Democrat Jacky Rosen and Republican Dean Heller have been locked in a tight battle for weeks. After Rosen led polls just weeks ago by 4%, momentum has shifted dramatically in the direction of the Republican post-Kavanaugh.
The most recent survey conducted by Emerson Polling (10/10-12) found Heller with a 7-point lead, 48-41, a 9-point swing in one month.
The Emerson poll follows a pattern of favoring Heller other surveys have indicated, including a NY Times/Siena poll (10/8-10) that found Heller ahead by 2 points (47-45) and an NBC News/Marist poll (9/30-10/3), which found him leading by 2 points (46-44). Just over two weeks ago, CNN found Rosen ahead by 4% (47-43).
If Republicans win Nevada and maintain control over their 50 "safe" seats, they will maintain their 51-seat majority.
Another key toss-up seat that appears to be trending Republican is Arizona's open seat, for which one poll shows Republican Martha McSally taking a lead on Democrat Kyrsten Sinema. A recent ABC 15/Ohio Predictive Heights poll showed McSally up by 6 points (47-41), though a Fox News poll found Sinema up by 2 (47-45) and CBS News/YouGov find the Democrat up by 3 (47-44).
The race between Democrat Claire McCaskill and Republican Josh Hawley in Missouri is likewise extremely close, a recent Fox News poll finding the candidates tied and RCP's average giving Hawley a razor-thin 0.4% edge.
The so-called "Kavanaugh effect" appears to have decisively impacted several key races, including the once "toss-up" seat in Tennessee, which has moved dramatically in the direction of Republican Marsha Blackburn since Democrats went all in on the smear campaign against Kavanaugh. A recent NY Times/Siena poll found Blackburn leading by a stunning 14-points after trailing just a month ago. The North Dakota race between Republican Kevin Cramer and incumbent Democrat Heidi Heitkcamp has also shifted strongly in the Republican's favor. A recent Fox News poll shows Cramer up by 12 points.