The dream of realignment has become the enemy of such compromises. It inspires politicians to claim sweeping mandates from highly contingent victories: think of Dick Cheney insisting on another round of deficit-financed tax cuts in 2003 because “we won the midterm elections” and “this is our due,” or the near-identical rebukes that President Obama delivered to Eric Cantor (“Elections have consequences — and Eric, I won”) and to John McCain (“the election’s over”) during the debates over the stimulus and health care.

The losers, meanwhile, wax intransigent, while hoping for a realignment of their own. After all, why cut a deal today if tomorrow you might overthrow your rivals permanently? Better to just say “no” flat out, as the Bush-era Democrats did with Social Security reform and the Republicans did with health care, and hope that the next election will deliver you the once-in-a-generation victory…

But in the wake of the weekend’s downgrade, we need them to govern as though that final victory might never quite arrive.