In the New York Times today, Edmund Andrews mentions that the firm Global Insight is predicting the GOP will only get 46 percent of the presidential vote:

“From a political point of view, the job market is not going to provide a lot of comfort at election time, especially for Republicans,” said Nariman Behravesh, chief economist at Global Insight.

Drawing on a model that correlates past economic performance and past election results, Global Insight is predicting that the Republican candidate for president in November will receive only 46 percent of the vote.

Such models have often been wrong before. But Republicans are keenly aware that Mr. Bush received little credit from voters for the last five years of good economic growth.

If Global Insight is predicting Republicans will get 46 percent of the two-party vote (as these models typically do), the result they are projecting would be comparable to Bill Clinton’s win over Bob Dole in 1996.

However, Democrats shouldn’t get so cocky. Lane Kenworthy, a professor of sociology and political science at the University of Arizona, notes that one of the least ad hoc presidential forecasting models — the “bread and peace” model of Douglas Hibbs, which combines war deaths with weighted growth in per capita real disposable personal income — actually projects a close election narrowly won by Republicans based on Kenworthy’s calculation of the “bread” figure at the end of 2007.

Here is its track record to date (the regression line excludes the outliers of 1952 and 1968):

Here are three 2008 scenarios Kenworthy plots (2008a is based on income through the end of the year, 2008b assumes the GOP is punished for deaths in Iraq, 2008c assumes a continuing economic slowdown through November) — as you can see, they are each extremely close to the magic 50% line:

The Yale economist Ray Fair also has a well-known election forecasting model. In his latest update, he projects a GOP two-party vote share of 48 percent. However, Fair writes that “it should be noted that the forecasts of inflation from [his econometric model] are more pessimistic than the current consensus view and the forecasts of real output growth are more optimistic.” (By contrast, if you project -2% economic growth, his model predicts a GOP presidential vote share of 45.4 percent.)

Of course, as Kenworthy notes, we shouldn’t take any of these forecasts too seriously. A model is a representation of how things worked in the past; there’s no guarantee of future performance, especially in an election in which no incumbent president or vice president is on the ticket. Also, each model has specific limitations that are worth keeping in mind. For instance, in terms of Hibbs’s model, Kenworthy correctly points out that growing income inequality means that per capita income has become an increasingly unrepresentative measure. (The main critique of Fair’s model is that the specification has been frequently modified for ad hoc reasons to maximize fit, as Hibbs discusses at some length in an unpublished paper.)

Still, the Hibbs projection in particular is a reminder that Democrats shouldn’t get cocky, especially if John McCain consolidates his hold on the GOP nomination tomorrow night. This election may be closer than anyone expects…