The Medicare and Social Security "problems" are two of perhaps the easiest solved issues in American politics right now, let's not pretend they require some unknown, wonky, new approach that has never been attempted ever before. The only reason no headway has been made on those issues and have subsquently been made "taboo" is because the ideology of the Right in this country has never actually been geared toward problem solving, but rather, focused on using problems as a vehicle to implement their ideological view of what government should do, rather than what it can do.
The left hasn't been remotely interested in dealing with it either. Every mention of what to do about the massive budget apocalypse of these programs is either demagogued ruthlessly as ___ hates old people/sick people/poor people/etc or just proposing some statement-making tax increase that does nothing to address the massive looming shortfall. No, the left has been raiding social security over the years just like everyone else.
A left-wing party would follow through on those solutions. Your problem is considering the Democratic Party as a left-wing party.
