N.H. Senate Race: Lots Of Polling, Little Movement

Since the New Hampshire primary on Sept. 9, there have been more than 11,000 poll interviews released in public polls on the U.S. Senate race. That's 1,200 more than the next state, Michigan, which is home to many more voters.

To put that in further perspective, about 457,000 voters actually turned out in the last midterm elections in New Hampshire. If turnout stays about the same as 2010, that means pollsters have talked to 2.4 percent of likely voters, just in the last month. And the 11,000 figure doesn’t include all the phone calls that led to those interviews, nor any internal campaign polling, interest group polling or persuasion calls done by the campaigns or outside groups. New Hampshire phones are ringing off their hooks.

Despite all the attention from pollsters and outside groups, the New Hampshire Senate race seems stable. When we last checked in on the campaign, several polls showed a tighter race than when Brown first threw his hat in the ring back in April. Since then, the Huffington Post Pollster model has held roughly steady, with Jeanne Shaheen maintaining a 4-point lead.

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Most recent media polls have shown Shaheen with leads of between 5 and 10 points. The only polls to show Brown actually in the lead have been conducted by Republican partisan pollsters, and those pollsters have a motive (and a tendency) to release only the results most favorable to their side.

The New Hampshire Senate race is attracting so much attention from pollsters and outside groups because it could be one of the elections that decides control of the U.S. Senate. Forecasting control of the Senate is the big game for the exploding industry of aggregators who rate, average and recycle others' polls. HuffPollster has a model, as does Nate Silver's FiveThirtyEight and the New York Times' Upshot, to name just a few. All three of these sites give the Republicans a narrow edge in winning control of the upper chamber. And if New Hampshire goes for Brown, the odds of a GOP Senate takeover rise considerably. In the HuffPollster model, for example, a Brown victory would give the Republicans a 66 percent chance of Senate control, up from 51 percent today.

But it's important to understand what the aggregators mean by these numbers. A forecast that Republicans have a 59 percent chance of taking control of the Senate (a recent FiveThirtyEight estimate) is not the same as a poll saying Candidate A has 59 percent of the vote. That 59 percent figure is a measure of the probability of that outcome actually happening in November. As Harry Enten of FiveThirtyEight helpfully analogized, right now the Republicans have the same chance of taking the Senate as a football team up by a single point has of winning with six minutes left in the game.

In other words, the GOP is in the lead, but the Democrats are still very much in the game. But Brown overtaking Shaheen would make staging a comeback that much harder. So far that hasn't happened, but if it does, you can expect to hear about quickly from one of the multitude of polls that will be driving New Hampshire households to leave their phones off their hooks between now and Election Day on Nov. 4.