President Romney is sure glad the "models" were correct in 2012.
^This. Also, never doubt the chances that the Republican candidate, probably Jeb or Walker at this point (more so Walker) will end up pushing social issues or generally gaffing it up right until November. Add in the fact that the GOP owns both houses in Congress and it makes oppo far easier for Hillary's team: just ran against the do-nothing regressivists and tie their candidate to D.C.
And don't neglect that even if the nominee or vp nominee don't gaffe it up, some Republican somewhere
will make an incredibly offensive statement regarding women, which the party will then refuse to clearly condemn.