Even before debates, electoral map appears largely written in stone

Many see potential for Wednesday's presidential debate to be a deciding moment in the 2012 election. From the Signal's perch here on Forecasting Mountain, we don't see a whole lot left to be decided.

Since we posted our first forecast of the state-by-state presidential election on Feb. 16, 2012, six months before the Republican Party even had an official nominee, only three states have flipped camps at any point in time. Virginia pointed toward the Republican nominee for several months during the summer, while both Florida and North Carolina have recently shifted to President Barack Obama's column. Almost all of the other 47 states have moved further in whichever direction they were leaning in February as the game clock has ticked down from more than 250 days to fewer than 40 until the election.

In February, we predicted that Obama would win re-election with 303 electoral votes. That estimate fell to 290 when Virginia flipped to the Republican column, and now stands at 347 with the restoration of Virginia and the addition of Florida and North Carolina.

Sources: Betfair, Intrade, HuffPost's Pollster, RealClearPolitics

The forecasts were flat until mid-May, as we had little new information to update the forecast, which was then totally reliant on economic and historical data that doesn't update daily. We then added in polls and prediction market data, which gradually takes over the forecast as Election Day approaches. The forecasts from February are the best estimation we can make about a generic Democratic incumbent running against a generic Republican challenger. By Election Day, the forecast is full of information about how the public views the actual Democratic incumbent against the actual Republican challenger.

Virginia and Florida were the least secure states for their respective candidates in our early forecast. North Carolina appeared to be a safe Republican win, but leapfrogged over three states we saw as less securely Republican to now favor Obama slightly. We expect this to happen in a few states each cycle. North Carolina was about 75 percent likely to vote for the Republican nominee in February, and now it is a little over 50 percent for Obama. Georgia, Indiana, and Missouri were all less safely Republican than North Carolina in February, but now appear safely pointing toward Romney.

Almost every other state has broken hard toward the likely winner in the past six months. Every day that the underdog candidate does not close the gap in a state, it becomes more likely to vote for the expected winner. As we have noted before, forecasting elections is less about uncertainty on Election Day than uncertainty over what can happen between the forecast and Election Day.

Arizona and Wisconsin are the only other states, besides Florida and North Carolina, that have not broken hard toward the likely winner since February. Arizona is lingering as very likely for Romney as Obama considers making a play for the state. Wisconsin is still slowly drifting toward Obama, but it briefly stalled its march when Romney nominated native son Paul Ryan as his running mate.

Follow the state-by-state and overall presidential predictions in real time with PredictWise.com.

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