First, make no mistake, both parties want to gut or kneecap Social Security. On the right (which is to say, among the rulers of the Republican party, not the voters) the Trust Fund is a big fat fruit, ripe for plucking and eating — $2.7 trillion and counting. That’s a lot of money to divert into the stock market, as Bush II tried to do in 2005. He was beaten back, partly because he was a Republican (keep that part in mind); but he gave it the college try.
On the “left” (as the Neoliberal rulers of the Dems like to brand themselves), the push is no less strong, but with slightly different changes on offer. The Wall Street billionaires would love to steal the Trust Fund outright, but you can’t sell that to Democratic voters, so when the “left” is in power, they don’t try to kill it so much as kneecap it, hobble it, cut its little hamstrings to keep it from walking.
The first Neoliberal president — the man who led the corporatization of the Democratic party — was Bill Clinton. He was also the first Democrat to rule after 12 years of Republican “revolution” that started in 1980, the year when everything changed. (Yes, you could call Carter a proto-neoliberal and be right, but that’s a tweak for this discussion.)
Clinton started the push to “fix” Social Security from the “left.