FDR understood that the Social Security tax was unnecessary to "fund" the program, but was needed to protect his signature program against GOP attacks and efforts to privatize it. RayGun's commission to "save" the program only doubled down on the reduction in middle-class spending power and never addressed the inherent problem of funding anything with Treasury bonds.
As the monopoly issuer of US dollars, the federal government can never involuntarily default on any obligation denominated in dollars. By extension, this applies to any program passed by Congress and signed by the President, regardless of the government's revenue position.
The only way to circumvent this economic reality would be to interject an artificial "fund" to limit the ability of Congress to set benefit levels. Any program that is so constrained is continually "in trouble" and subject to attacks by the GOP. What FDR saw as "protecting" Social Security was turned into a negative by the falsehood of bonds as a "funding" mechanism for federal spending.
The GOP is not likely to let up its attacks, so the best way to protect economic security for our elderly is to openly and boldly present the truth of how the federal government spends. The GOP understands this, or it wouldn't continually push tax cuts and budget busting spending on the 1%. GOP Presidents have often spoken the quiet part out loud and stated that "deficits don't matter" (Bush and Cheney) and "We make the money, so default is not possible" (Trump).
Even the conservative rock star, Allen Greenspan, pushed cutting the program and privatizing most of it until he was under oath. Then, his entire tune changed and he admitted that we are only constrained by our ability to provide the goods and services seniors would demand, not by economics or any limitation to Congress' ability to create money.
