Well, show me someone in Congress who doesn't oppose any changes? Any mention of cutting benefits or making significant (and needed, in my opinion) changes to the current SS system is political suicide. No one will touch that with a 100' pole.
'Changes', especially if DJT says it, will be disseminated across the media as 'ending SS as we know it', regardless of what he actually says. 'No more SS for Grandma!!!'. The Dims, on the other hand, want to give everyone a 'basic income' so 'SS for everyone!'. Well, the SS system is busted and will be flat broke in about 6 years. What could possibly go wrong by making sure everyone is dipping into that dried up well? Oh, let's not forget those folks who've crossed the border illegally and have not paid one bloody cent into the system. By all means, let's give them some cash, too.
The first step to making changes that will ensure the sustainability of the SS program is to realize that the current system cannot be fixed. Keeping some important pieces and making sure those most in need and receiving current benefits don't take the brunt would be job 1. After that, funding, privatization, COLA, income that is taxed, means testing, etc. all need to be on the table or the whole thing will implode. Same with Medicare, another program teetering on the edge of collapse and expected to collapse within the next 5-7 years. Running up >$1T in annual deficits with 10's of $T of unfunded obligations (pensions, SS, Medicare/caid) is lunacy. Nobody on either side of the aisle cares just so long as they can line their own pockets. Certainly neither of the frontrunners for President are going to cut spending or even propose cutting spending. The only thing I can say is that Trump will overspend less insanely than the Cackling idiot.