This is why Obama is now the second president in a row to win election as a uniter — and then campaign for reelection by trashing his opponent and herding his party’s base to the polls.

No doubt the president would reject this comparison with George W. Bush. But I mean it as a statement of reality, not an accusation. This is just the way presidential politics works in a polarized milieu. And for all his charisma and good intentions, Obama could not transform that dynamic, or even resist it…

Both men promise the party faithful that electoral victory will mean policy triumph; if recent history has shown anything, though, it is that neither party is strong enough to impose its agenda. Nor is there much to be gained from conventional legislative compromise. The country’s financial problems are too great for piecemeal solutions, and the parties’ differences on how to solve them are too big to split.

Our predicament calls for a different kind of politics — in the tradition of the sectional Great Compromises of pre-Civil War America, including the deals embodied in the Constitution itself.