Unlikely Voter

Conservative views on polls, science, technology, and policy

Senate Projection for September 13

With the House update done, it’s time to move on to the new Senate update. Last week the pace of Republican gains slowed, as the GOP gained less than a full seat in my projection since I started running it. But the chance of a Republican majority has climbed every time, so let’s see if that still holds.


Senate right now: 59 D-41 R.

Seats up right now: 19 D-18 R.

Seats therefore not up: 40 D-23 R.

Minimum result needed for majority: -9 for Democrats, +10 for Republicans.


I’m going to work off the polls when they’re available, working from Real Clear Politics, giving double weight now to Likely Voter polls, and make guesses otherwise. That’s usually easy because the seats that aren’t polled are typically safe. Changes from last time will be in boldface.


AL: Richard Shelby: Primaries done. Lead has grown to +32 in Rasmussen. 99.9% R victory.

AK: Lisa Murkowski (primaried): Primaries done. Joe Miller leads the early polling but not quite overwhelmingly. 80% R victory.

AZ: John McCain: Primaries done. McCain maintaining 20 point leads. 99% R victory

AR: Blanche Lincoln: Primaries done. John Boozman up 20+ in polling. 99.9% R victory (from 99%).

CA: Barbara Boxer: Primaries done. Likely Voter polls now favoring Fiorina very slightly. 50% R victory (from 33%).

CO: Michael Bennet: Primaries done. Good poll for Bennet from Public Opinion Strategies. 60% R victory (from 75%).

CT: Chris Dodd (retiring): Primaries done. Blumenthal stabilized for now against McMahon gains. 10% R victory (from 15%).

DE: Joe Biden (resigned): Primaries in progress. Castle still up, but O’Donnell well down, and their primary is very close now. 50% R victory (from 95%).

FL: Mel Martinez (resigned): Primaries done. The wrong Democrat won for Charlie Crist. 85% R victory.

GA: Johnny Isakson: Primaries done. Isakson lead in the 20s save for one Insider Advantage poll. If it’s confirmed by others this rating will move further. 99% R victory.

HI: Daniel Inouye: Primaries in progress. Inouye nearing 70 in poll. 0.1% R victory.

ID: Mike Crapo: Primaries done. Crapo lead hovering around 40. 99.9% R victory.

IL: Barack Obama (resigned): Primaries done. Kirk edges ahead again. 55% R victory (from 50).

IN: Evan Bayh (retiring): Primaries done. Dan Coats lead growing. 99% R victory.

IA: Chuck Grassley: Primaries done. Grassley rebounds from one bad poll. 99% R victory.

KS: Sam Brownback (retiring): Primaries done. Republican Jerry Moran leading all polls. 99.9% R victory.

KY: Jim Bunning (retiring). Primaries done. Randal Paul’s lead seems to be growing, but two good polls outweighed by the CNN/Time tie. 85% R victory.

LA: David Vitter: Primaries done. Vitter gets a bounce in Rasmussen. 95% R victory.

MD: Barbara Mikulski: Primaries in progress. Mikulski’s primary opponent’s internal even has her ahead. 0.1% R victory.

MO: Kit Bond (retiring): Primaries done. Blunt marching on from one bad poll I didn’t trust anyway. 85% R victory.

NV: Harry Reid: Primaries done. Clean sweep of small poll leads for Reid. 35% R victory (from 45%).

NC: Richard Burr: Primaries done. Burr takes a big lead in one Rasmussen poll. 85% R victory (from 70%).

ND: Byron Dorgan (retiring): Primaries are done. John Hoeven leads by so much he breaks the graphics in my analysis tool. 99.9% R victory.

NH: Judd Gregg (retiring): Primaries in progress. Kelly Ayotte bounced back in the general election matchup, but Lamontagne surges in the primary and lowers the percentage. 80% R victory (from 85%).

NY: Chuck Schumer: Primaries in progress. Schumer’s lowest lead in any poll was 19. 0.1% R victory.

NY: Kirsten Gillibrand: Primaries in progress. Gillibrand leads every matchup. 1% R victory.

OH: George Voinovich (retiring): Primaries done. Portman extends his lead. 85% R victory.

OK: Tom Coburn: Primaries done. Coburn lead approaching 40. 99.9% R victory.

OR: Ron Wyden: Primaries done. Recent polling very good to Wyden. My thoughts of this being a sleeper GOP victory seem to have been premature. 1% R victory.

PA: Arlen Specter (primaried): Primaries done (especially for Specter). Pat Toomey finally hits double figures in one poll. 85% R victory.

SC: Jim DeMint: Primaries done. No polling I can find. Alvin Greene’s indictment seems to have diminished interest in this race. 99.9% R victory.

SD: John Thune: Primaries done. Unopposed. 100% R victory.

UT: Bob Bennett (primaried): Primaries done. Lee lead down to 25 in the sole poll. 99.9% R victory.

VT: Patrick Leahy: Primaries in progress. Leahy up 35. 0.1% R victory.

WA: Patty Murray: Primary done. Rossi takes another poll. 60% R victory.

WV: Robert Byrd (died): Special election in progress. Manchin lead cut from 16 to 6 to 5 now in sole poll. 30% R victory (from 25%).

WI: Russ Feingold: Primaries in progress. Still no new polls other than Rasmussen’s with Johnson’s small lead. 45% R victory.

The simulation

100,000 trials using the probabilities above.


For the third straight week a 7 seat Republican gain is most likely according to my estimates. In this case though, the GOP has slid back to the result of two weeks ago, with 6 being more common than 8. Those three outcomes of R+6 to R+8 account for 59% (58,632/100,000) of the curve. 4% (4,434/100,000) of the trials gave Republicans a Senate majority, down from last week’s 6%, and again a return to the result of two weeks ago. Only 5 of 100,000 trials gave Democrats a gain.

So the string of Republican gains is over as of this week, as the party backslid a bit. Democrats were helped quite a bit by turmoil in the Delaware and New Hampshire primaries, though that change was partially offset in states like California and North Carolina. But still: depending on how tomorrow’s primaries go Republicans will might gain back those losses, or give back even more ground next week.


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