none of the parties can afford losing voters on social security

The solution to this problem is to pitch SS as already in crisis and to campaign on a “fix” that makes it more solvent by reducing the number of people who rely on it.

Same story every time.

Because the problem is so big and there are so many consequences across so many districts to a change in SS policy, the easiest thing for Congress to do in the face of any proposed changes is to punt. However, we’ve seen SS cut successfully in the past. Reagan’s “fix” to SS was to raise the retirement age (effectively a cut) and shift more of the tax burden onto the employees. Bush Jr came very close to a full scale privatization of the Trust, effectively turning the broad social program into a series of individualized 401k-esque savings accounts that the federal government would never suffer liability over. Obama can dangerously close to a big cut to retirement payments as part of the 2013 Debt Ceiling negotiations, only failing because Tea Party Republicans scuttled the deal and forced a continuing resolution to keep the government funded. Trump toyed with privatization again, with Paul Ryan’s House championing a number of big cuts to Social Security that were ultimately parsed down to back-door cuts by way of how inflation was calculated (but this still ended up shaving billions off the next generation of program operations).

These cuts are always pitched as methods of preserving the program. They inevitably come at the expense of taxpayers, making the system less and less attractive to defend.