John Edwards wins the 2008 nominations and easily beats McCain in 2008. His presidency went moderately well and he appears on track to narrowly beat Romney...but the affair scandal comes out 5 days before the election. How well does he fare? Does he subvert expectations and win re-election or does he lose in a landslide or in between?
I'd say the scandal doesn't hurt him as much as it probably should but he still loses.
His narrow leads in Nevada, New Mexico, Iowa, Ohio, Pennsylvania and New Hampshire all but evaporated. Romney, on virtue of being a fellow Northeasterner in a good night for him even captures Maine's 2nd district. Edwards does narrowly hold on to most of the Upper Midwest but it's nowhere near enough. Popular vote I think is Romney 51, Edwards 47 so almost a complete reverse from IRL 2012. Romney's closest wins are Nevada, New Mexico and Maine's 2nd district. He edges out wins in the latter two by slightly more than a point.
Edwards' closest wins are Wisconsin, Minnesota and Michigan. Wisconsin is the closest state of the election as Edwards edges out by just over 15,000 votes. Minnesota and Michigan are won by about 1.5% a piece.
A solid 317-221 electoral victory for Romney.