Ray Fair of Yale University runs a much-respected election forecasting model. It takes into account such factors as the power of incumbency, real per capital GDP growth, etc. Here is his just-updated forecast that shows President Obama has only a 50-50 chance at winning a second term. According to the Fair model, a so-so economy going forward means Obama would get just 50.0 percent of the two-party vote (noted as “VP” in the below chart) vs. 53.4 percent in the summer due to the slowing economic recovery…