As of today, gay marriage is once again a partisan issue at the heart of a presidential election campaign. Many Republicans who might have had flexible opinions as of yesterday are now going to find themselves psychologically inclined to move towards the party line. Mitt Romney will be forced, within the next hours or days, to come out with a full-throated argument against gay marriage. Republican office-holders will have to vocally support that position. Republican media outfits (Fox News, conservative talk radio, RedState and so forth) will have to join the attack. Millions of GOP voters who otherwise might have gradually reconciled themselves to gay marriage within the next few months will be held back by the ideological alignments created in this presidential campaign.A good example of unintended consequences.