“If Ryan-Romney win, they would certainly pursue a major tax cut plan,” Bob Bixby of the anti-deficit pressure group The Concord Coalition agreed. “It would be very difficult to do entitlement reform and tax reform at the same time.”

He said the key variable is the size of a GOP Senate majority after the elections, and whether Senate Minority Leader Mitch McConnell (R-Ky.) — who could become the chamber’s majority leader if Republicans capture the majority there — can spare some defections on entitlements.