"Forgiving privately held debts" sounds an awful lot like "taking (stealing) from the lender". That probably would not pass a Supreme Court review. (No taking without just compensation.)

No major or even minor political party is talking about just "canceling" the debt without paying the lenders. The lenders are still going to get paid so this isn't a "taking". The debt is just transferred to the the US balance sheet instead of being held by the student.

I would entirely agree but I'm not sure the average Bernie, Cortez, or Warren supporter would.

I have definitely heard people advocate for a total jubilee on student loan debt.

I do agree that the current Supreme Court probably wouldn't let it happen.

Well, in fairness, Bernie is not responsible for everything every one of his supporters say. (He is responsible for making it clear when what he means is different from what his supporters think.)

The full plan isn’t out but they’ve implied it would be public & private debt as well as making community & public colleges tuition free going forward.