Romney camp hoping for a systematic polling bias in Ohio

In the last two days, six new polls of Ohio voters have been released, five of which favor President Barack Obama, by leads of 6 points, 4 points, 4 points, 3 points and 2 points. The last reports a tie, from right-leaning Rasmussen, which gave former Gov. Mitt Romney a 2-point advantage last week. Obama now has a 3.1 percentage point lead in Pollster's average for Ohio and a 2.9 percentage point lead in the RealClearPolitics average for Ohio.

A 3 percentage point lead is hardly an insurmountable margin for Obama. But it has been so consistent over the past several weeks that Romney ought to be hoping that the polls favor Obama on a systematic basis by overestimating the turnout of respondents with demographics that favor him. This is certainly possible, but it would mean that many different polling institutions are making similar mistakes. The outcome of Ohio, then, will be as much a referendum on the art of polling as it will be on the art of the presidency.

Sources: Betfair, Intrade, IEM, HuffPost Pollster and RealClearPolitics

The story is the same in Wisconsin; Obama has gone from about 75 percent likely to win to over 90 percent in our model, based on the strength of consistent polling. Wisconsin is one of Romney's better hopes for victory should he lose Ohio, but we see this as unlikely. Wisconsin's likelihood of victory moves closely with Ohio's likelihood of victory, making it unlikely that Romney would ever pluck Wisconsin without also winning Ohio. Both states respond to the same national trends and have strong regional similarities.

As the election enters its final days, Obama is over 70 percent likely to win re-election. Romney holds a slight lead in Florida, but he must capture both Virginia and Ohio as well, and time is slipping away.

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David Rothschild is an economist. He has a Ph.D. in applied economics from the Wharton School of Business at the University of Pennsylvania. Follow him on Twitter @DavMicRot.