I haven’t been tracking Senate races, but I thought I would do a Senate projection based on the most recent polling in each state.
Senators not up for election looks like the following:
Republicans 37, Democrats 30
Based on my projections, here will be the makeup of the incoming Senate class:
Democrats and Democrat leaning Independents 24, Republicans 9
Leading to a new Senate of:
Democrats and Democrat leaning Independents 54, Republicans 46
Which, of course, would be a gain of one seat by the Democrats. However, some of the following races are very close, so one should most definitely not take the above projection with any certainty.
Now, here is the projections for the Senate races, with notes following:
Arizona: Flake (R): 47.7%, Carmona (D): 45%
California: Feinstein (D): 53.7%, Emken (R): 34.4%
Connecticut: Murphy (D): 48.7%, McMahon (R): 43.4%
Delaware: No polls, but Carper (D) is a heavy favorite
Florida: Nelson (D): 49.6%, Mack (R): 43.3%
Hawaii: Hirono (D): 54.1%, Lingle (R): 38.8%
Indiana: Donnelley (D): 44.9%, Mourdock (R): 41.9%
Maine: King (I): 49%, Summers (R): 34.1%, Dill (D): 11.8%
Maryland: Cardin (D): 54%, Bongino (R): 23.2%
Massachusetts: Warren (D): 49.8%, Brown (R): 46.8%
Michigan: Stabenow (D): 53.1%, Hoekstra (R): 39.8%
Minnesota: Klobuchar (D): 60.6%, Bills (R): 29.5%
Mississippi: No polls, but Wicker (R) is heavy favorite
Missouri: McCaskill (D): 48.9%, Akin (R): 41.2%
Montana: Tester (D): 46.8%, Rehberg (R): 46.4%
Nebraska: Fischer (R): 52.3%, Kerrey (D): 43.7%
Nevada: Heller (R): 45.9%, Berkley (D): 42.9%
New Jersey: Menendez (D): 51.7%, Kyrillos (R): 32.8%
New Mexico: Heinrich (D): 49.3%, Wilson (R): 43.5%
New York: Gillibrand (D): 66.3%, Long (R): 23.3%
North Dakota: Berg (R): 46.8%, Heitkamp (D): 46.7%
Ohio: Brown (D): 49%, Mandel (R): 44.6%
Pennsylvania: Casey (D): 47.6%, Smith (R): 42.6%
Rhode Island: Whitehouse (D): 55.6%, Hinckley (R): 32.3%
Tennessee: Corker (R): 59%, Clayton (D): 21%
Texas: Cruz (R): 53.5%, Sadler (D): 37.2%
Utah: Hatch (R): 63%, Howell (D): 26%
Vermont: No polls, but Sanders (I) is heavy favorite
Virginia: Kaine (D): 48.6%, Allen (R): 46.7%
Washington: Cantwell (D): 58.2%, Baumgartner (R): 36.1%
West Virginia: Manchin (D): 66%, Raese (R): 27%
Wisconsin: Baldwin (D): 47.4%, Thompson (D): 46.5%
Wyoming: No polls, but Barasso (R) is heavy favorite
Clearly the two closest races of the night will be in Montana and North Dakota. With other possible races to watch in Arizona, Connecticut, Florida, Indiana, Massachusetts, Missouri, New Mexico, Ohio, Pennsylvania, Virginia, and Wisconsin.
The race is North Dakota is virtually a tie, separated by 0.1%. The Republican “wins” the projection since he is the one ahead, but, really, flip a coin on that one. In Montana, Tester may be winning the average by 0.4%, but being the incumbent, and not even at 47%, you have to favor Rehberg in the end there, I think, which reduces the Dem margin in the Senate to 53-47.
Incumbents have close races, but probably should win in Florida, Missouri, Ohio, and Pennsylvania, though Casey is probably the most endangered out of those four.
One place where the incumbent looks likely to lose is in Massachusetts. While it’s not impossible for incumbents who are down going into election day to come back and win, it certainly isn’t all that likely. And he’s down by 3 AND Warren is near 50%, which makes it even less likely.
That leaves non-incumbent races in Arizona, Connecticut, Indiana, New Mexico, Virginia, and Wisconsin.
In Arizona, Flake is ahead by about 2% in a lean GOP state, so you figure that has to lean to his advantage. However, if there is a late democratic surge, Carmona could pull the upset in Arizona.
In Connecticut, Murphy leads by 5%, and it would take a pretty significant final GOP surge to give McMahon the victory. The same is pretty much true in New Mexico, where Heinrich is up about 6%
In Indiana, you have the weird situation where Mourdock is down, but his opponent Donnelley is only at about 45% in the average. That one could really go either way, especially given that it’s in the GOP state of Indiana.
In Virginia, Kaine is leading Allen by about 2% in a state that has been trending more toward Obama over the past week. This race could very well go the same way Virginia goes in the Presidential race, though Kaine perhaps has about 1/2% to 1% more give than Obama does if things swing to the GOP.
Wisconsin sees a very similar situation as Virginia, with Baldwin leading, but only by about 1%. If there is a surge in Wisconsin in either direction on election day, that will likely push that particular candidate over the edge.
Overall, in the end the maximum Democratic seats is probably 57, if they are able to save Tester, and then swing Arizona, Nevada, and North Dakota to their side. The Republicans maximum seats is probably a 50-50 tie if they can swing Indiana, Montana, Virginia, and Wisconsin all their way. I would find doing any better than that a pretty big long shot.