But tax-reform-first makes possible the compromise that eluded John Boehner and Barack Obama. Boehner was willing to increase revenue by $800 billion. Obama was reputedly ready to raise the Medicare age and change the Social Security cost-of-living formula.

Remember: Tax reform will already have slashed rates radically. In one Simpson-Bowles scenario, the top rate plunges to 23 percent. Conservatives could at that point contemplate increasing net revenue by slightly tweaking these new low rates, say, back to Reagan’s 28 percent, still much lower than the current 35 percent and Obama’s devoutly desired 39.6 percent. The deviation from revenue neutrality would yield new tax receipts for the Treasury, in addition to those resulting from the economic growth stimulated by the lower rates.

Democrats would have to respond by crossing their own red line on entitlements. That means real structural changes. That means raising the Medicare and Social Security ages, indexing them to longevity (until 70 becomes the new 65) and changing the inflation formula. Perhaps even means-testing Social Security (after one has recouped what one originally paid in).