Enten: But What About the Incumbent's Margin?

02/26/2010 09:44 pm ET | Updated May 25, 2011

Harry Joe Enten is a junior at Dartmouth College and will be interning with this spring and summer.

Yesterday, Nate Silver posted a well thought out post on why the 50% incumbent rule no longer applies. I think Nate's post is straight on, but I think that he misses a potentially larger point. In his chart, you'll notice something very interesting: no incumbent from 06, 08, or 09 won when trailing by more than 1.5 points in the January to June average of polls. I think that points to potentially very large problems for Democrats in the 2010 United States Senate Elections. Why? If current polling averages hold through June, the Democrats would be on the verge on losing the United States Senate, according to Silver's findings. What follows is a simple rundown of the top (and some not so top) United States Senate races involving seats held by Democrats. I apply Nate's rule of averaging all the polls available (including partisan ones). I supply a two month (starting in January as Nate did) and six month (using length of time of) Nate's average (when available) to try and catch short and long term trends. To be fair, I take only the highest polling Republican candidates. I don't intend this to be a be all end all, but the results are still amazingly scary for Democrats.

I find 6 Democratic incumbents who would most likely lose re-election, if the polling averages held through June. One Democratic incumbent does lead, but she is also going to have a difficult time in her fight for re-election.


1. Arkansas- Democratic Senator Lincoln trails by an average of 21.5 points since January to Rep. John Boozman and 10 points since January and 5.4 points since September to Gilbert Baker. Not only is Lincoln in trouble, but her trouble seems to be getting worse by the day. Unless a dramatic turn occurs in the polls (and considering Boozman is the likely Republican candidate), Lincoln is probably a goner.

2. Nevada- Senate Majority Leader Harry Reid is in major trouble. He had trailed potential Republican candidates Danny Tarkanian by an average of 7.8 points since January and 6.9 points since September and Sue Lowden by 7.8 points since January and 8.2 points since September. Such polling and past history would argue that Reid is dead in the water; however, the emergence of Tea Party candidate Jon Ashjian has thrown the race somewhat into doubt. Reid still trails both candidates, but, with Ashjian in the race, Lowden leads by only 5 and Tarkanian only leads by 1 point in the only poll including the Tea Party candidate. Still, Reid's position is precarious at best, and he would almost definitely lose to Lowden, if the averages held through June.

3. Colorado- Senator Michael Bennet is not an incumbent in the traditional sense (he was appointed to the post), and both appointed Senators Bob Menendez and Roger Wicker were among the incumbents who performed significantly better than the average of polls between January and June indicated. Bennet is also facing a primary challenge from Andrew Romanoff. If Bennet makes it out of the primary (an if, but the only poll conducted so far indicated Bennet leads), he trails by 9.5 since January and 9.3 points since September to Republican Jane Norton, 2.3 points since January and 2 since September to Tom Wiens, and 2 points since January and 0.8 since September to Ken Buck. If those leads hold (and they seem to slightly be expanding), Bennet is in major, major trouble especially against Norton. Ramonoff does not do much better; he trails Norton by 6.8 points since January and 7.7 points since September, 1.7 points since January and 1.5 points since September to Tom Wiens, and 2 points in both the January and September averages to Ken Buck. Romanoff seems to be a slight underdog, especially against Norton.

4. Pennsylvania- Republican turn Democrat Arlen Specter is in as in much troubled as the 2010 New York Mets. He trails Republican challenger Fmr. Rep. Pat Toomey by 8.8 points in an average of the polls since January and 4 points since September. Both of these averages would render him on life support applying Silver's standard come June. Specter is being challenged in the Democratic primary by Congressman Joe Sestak. Specter currently leads Sestak in that primary by 20 points (a lead, which is growing). If Sestak somehow won the primary, he trails Toomey by an average of 12 points and 6.9 points in polls conducted since January and September respectively. In a Republican year, it would be very difficult for Sestak to make a comeback from being this far back.

5. New York- Senator Kirsten Gillibrand, like Senator Bennet, is an appointed Senator in trouble. Her negative net approvals indicate a good challenger would have a fair shot. The mostly unheard of Bruce Blakeman trails Gillibrand by 22 points and 24.7 points in the polling average since January and September respectively. Potential candidate Fmr. Governor George Pataki would make it a race. He leads Gillibrand by 5.5 points in the average since January and 1.4 points in the average since September. Pataki leads the other potential Democratic candidate Harold Ford (who has trailed by 14 points or greater in every primary poll against Gillibrand) by an even larger 14.8 points since January. If Pataki does get into the race, he would be a very formidable challenger. Of course, even if Pataki does not enter the race, Gillibrand's approvals leave her in a vulnerable position.

6. Washington- Senator Patty Murray is not the first Senator you think of as in danger. The Cook Political Report, Rothenberg Political Report, and Larry Sabato's Crystal Ball all have this race rated as safely Democratic, but one Republican challenger could make it a race. Republican Dino Rossi leads by 2 points over Murray in two recent polls. Rossi nearly won the Governor's mansion in 2004, losing in a recount, and he only lost by 6.5 points in 2008 when President Obama carried the state by 17 points illustrating his appeal as a statewide candidate. If the recent polls hold, Rossi could give Murray one heck of a fight.

7. California- Democrat Barbara Boxer leads her strongest challenger Republican Tom Campbell by on an average of 5.5 points in polls taken since January. Boxer has the edge in this matchup, but the Cook Political Report and Larry Sabato's Crystal Ball have the race at only Lean Democratic. Keep in mind, Republicans Carly Fiorina and Chuck DeVore poll considerably weaker. As such, Republicans should hope that Campbell wins the nomination, if they are looking for the candidate with the best shot at winning. He leads in recent primary polls.

The two and six month polling averages indicate that the Republicans are in a position to defeat six Democratic incumbents. This position seems to have strengthened over the last two months. In two states, New York and Washington, they need to hope they can recruit two candidates. If they do and the averages hold, Republicans could easily be up to 47 seats in the United States Senate.

When you combine these races with open Democratic seats, the Democratic majority looks like it could fall.


1. North Dakota- Republican Governor John Hoeven leads all opponents by at least 21 points, and he is over 50% in all polls conducted since January. He'll win unless a divine miracle happens for the Democrats.

2. Delaware- Congressman At-Large (meaning he represents the entire state) Mike Castle leads Democrat Chris Coons by an 22.7 and 20 points in polls conducted since January and September respectively, and he has been over 50% in every poll ever conducted in this race. Coons is not as dead as the Democrats in North Dakota, but he has a very high hill to climb.

3. Indiana- Republicans Fmr. Senator Dan Coats and Fmr. Representative John Hostettler lead both Democratic Congressmen Brad Ellsworth and Baron Hill by at least 14 points in the only poll conducted since Democratic incumbent Evan Bayh announced he was not running for re-election. We'll have to see if this poll is an aberration, but the Cook Political Report already has this seat leaning Republican.

4. Illinois- Republican Congressman Mark Kirk trails Democrat Alexi Giannoulias by 0.2 points in the polling average since January, but Kirk leads Giannoulias by 0.4 points in the average since September. It could go either way.

In conclusion, I am by no means saying that the Republicans will take back the Senate; however, the polling in conjunction with past results indicate that it not that long of a shot that they do. Democratic candidates seem to be consistently weak over the last six months, and the Republicans seem to be moving into a stronger position in the last two months. Keep in mind that in 06 and 08, Democrats pretty much swept all the hotly contested races (save Tennessee in 06 and Georgia in 08. In these years as well as 1994, the party who lost seats (Democrats in 1994 and Republicans in 2006 and 2008) did not win a single seat belonging to the other party.

If the national environment for Democrats does not improve, these polling averages probably will not get that much better for Democrats. And if the averages do not get better, Silver's findings show the Republicans are at least in a position to win 10 seats and take back the United States Senate.