...that the GOP was the more politically unified party, while the Democrats where a mismatched coalition of various interest groups.

Well I think that might still be true of the Democrats, but this year is really shining a bright light on the one enormous fissure that DOES exist in the Republican Party. The only thing that the Captains of Industry have in common with the blue collar members of the GOP is Social Conservatism. That has worked well enough during relatively good economic times, but it is clearly failing them now.