According to this breakdown we would need to ELIMINATE social security (738 billion), all income security (567 billion), medicare (498 billion), medicaid (381 billion) and gut the budgets of near every other agency and department to make the other 500 billion up. That is assuming zero growth, which isn't likely. More likely than not our national debt ceiling will be increased, as will our debt and then the net interest on the debt. This amount is already almost doubling every year, and would cover 1/2 the 500 billion that would warrant gutting. Until we eliminate the deficit we will borrow more too.
So IMO the kinds of departments and agencies, like the Department of Education and teacher salary, that grow every year at an unsustainable exponential rate must be also eliminated. Yes I am for eliminating Public Education. I also don't think that so many cuts would be necessary, as I believe the tax revenue from the ensuing prosperity from the government not meddling would offset the growth, but this would be too difficult to quantify.