The defining element of Sunday night’s debt-limit deal is not what happens now, but what it sets up for the next five months: an all-out war between tax increasers and entitlement cutters, fought on the battlefield of a 12-member congressional “supercommittee.”

With both wings of the political spectrum opposed, President Obama and House Speaker John A. Boehner had to ditch talks that would have meant tackling taxes or entitlements in the short term. But the agreement they reached Sunday wrote the rules to ensure it happens now, in that committee.