A great Ron Brownstein column on the demographic questions hanging over the presidential race ends with a lame sixth question: "Can anyone win a mandate to govern?"
The answer is "no." A mandate is not a real thing, so there's nothing a candidate can do—up to and including a Democrat carrying North Carolina and Indiana—to win one. Probably the best way to think of a mandate is as a historical artifact of the poorly sorted congressional politics of yore. Politicians in that framework were cross-pressured between partisan and ideological loyalties. A president with a "mandate"—think Ronald Reagan in 1981 or Lyndon Johnson in 1965—could unify the ideological factions within his own party while fracturing the other side's coalition. Modern politics just doesn't work like that. Olympia Snowe, Scott Brown, Susan Collins, and Mark Kirk all vote a more reliably conservative line than Ben Nelson, Joe Manchin, or Claire McCaskill. Different politicians disagree with each other about different things, but the parties are basically coherent ideological teams. And although there may be compromises to be forged, there are no mandates to be won.