Just how extreme are Mitt Romney’s budget proposals? The Center for Budget and Policy Priorities breaks down what exactly is implied by Romney’s commitments to slashing tax rates, increasing defense spending, keeping Social Security untouched, and balancing the budget…and the results are, well, in Romney’s words, “severe.” At least, if you take Romney at his word. I have my doubts.

I’ll start with what Romney says he would do, as interpreted by CBPP:

If policy­makers exempted Social Security from the cuts, as Governor Romney has suggested, and cut Medicare, Medicaid, and all other entitlement and discretionary programs by the same percentage, then nondefense programs other than Social Security would have to be cut 29 percent in 2016 and 59 percent in 2022…The cuts that would be required under the Romney budget proposals in programs such as veterans’ disability compensation, Supple­mental Security Income for poor elderly and disabled individuals, SNAP (formerly food stamps), and child nutrition programs would move millions of households below the poverty line or drive them deeper into poverty.  The cuts in Medicare and Medicaid would make health insurance unaffordable (or unavailable) to tens of millions of people.

But it’s not just anti-poverty programs that would get slashed; as CBPP’s Paul Van de Water says, it would include such things as “elementary and secondary education, law enforcement, veterans’ health care, environmental protection, and biomedical research.” Sure, Romney could protect any particular program — CBPP is just assuming equal across-the-board cuts — but only at the expense of another one.

CBPP claims that Romney’s cuts would be “substantially deeper” than those in the House-passed Ryan budget. I wouldn’t put it that way; remember that Ryan’s budget essentially shuts down the federal government other than the military, Social Security, and health entitlement programs by 2050. Instead, I’d say that Romney’s cuts would be quicker than Ryan’s.

CBPP also notes, correctly, that it could be a lot worse. The big scoring question is how to evaluate Romney’s tax proposals. The former Governor says that he would cut rates, and pay for it by eliminating tax expenditures, although he rules out some areas for savings. CBPP guesses that Romney would wind up recovering half the lost revenues from tax rates, but the supporting argument makes it clear that it’s implausible that Romney would achieve anywhere near that much.

So when all is said and done, what would a Romney budget really look like if he had majorities in Congress? There’s no real way of knowing, but fifty years of GOP history suggests that the tax rate cuts would happen, and programs that benefit Democratic constituencies would be hit hard. However, the offsetting revenues would never materialize, and neither would broader spending cuts  – and so deficits, especially projected long-term deficits, would soar.

Now, that’s not what Romney (or Paul Ryan) says. But any time you try to pin them down about which programs they would cut or which deductions they would eliminate, it’s foreign aid, PBS, and lots of hemming and hawing and harrumphing about waste and fraud, and how dare you accuse us of cutting such-and-such popular program. So after a while, you start to get the picture. At any rate, that's the choice: assuming Romney’s specific commitments to tax rate cuts and defense spending are for real, then he'll either be blowing up the deficit or slashing spending on very popular programs. There really is no other possibility.