Republicans have always hated Social Security and Medicare (go here for the history of that).
President George W. Bush tried to privatize Social Security, but the more he campaigned for his “reform,” the less public support it had. Other Republican efforts to undermine these popular programs invariably came to a political dead end, too.
So now they’re taking a stealth approach. A Vox article (here) says,
“What Republicans need to cut Medicare and Social Security is … a forcing mechanism. Trump’s fiscal priorities would help provide them with precisely this. The Republican nominee is committed to slashing federal revenue across the board and has repeatedly flirted with payroll tax cuts that would gut funding for Social Security and Medicare. These measures would expedite the programs’ insolvency.”
Then,
“If Republicans control Congress when the conflict between avoiding all tax increases and sustaining entitlement benefits becomes irreconcilable, they will be liable to cut the latter ….”
The Social Security and Medicare benefits paid to current retirees are largely financed by payroll taxes paid by current workers. But as the ratio of retirees to workers increases, the gap between benefit payouts and tax revenues grows, eventually draining the surplus tax revenues stored in the Social Security and Medicare trust funds.
What this says is, if Republicans can further erode those tax revenues by cutting payroll taxes, they can force benefit cuts. And if they can increase general budget deficits by cutting taxes for rich people, and by other devices such as eliminating income taxes on tips and social security benefits, that can prevent future Congresses from making up the Social Security and Medicare deficits from general tax revenues.
It’s an underhanded way of getting rid of, or at least paring back, Social Security and Medicare. And if you vote for Trump in 2024, that’s what you’re voting for. Even though he says he won’t cut those programs, he’s absolutely in cahoots with the reactionaries in his party (and in Project 2025) who are scheming to do just that.