Time for an update on the GOP War on Budgeting: Mitt Romney said today that budget analysts who have found his tax plan would massively increase the deficit and make the tax code less progressive were jumping the gun because his proposal “can’t be scored.” As Brad DeLong says, “Romney has really put on the big shoes and the rubber nose.”

TPM’s Brian Beutler has the full story. Romney’s argument is that the details of his proposal would be worked out with Congress, and so a proposal without details can’t really be assessed. But outside of how cowardly that is — Romney is proposing that as president he’ll duck responsibility for the costs of his program — what really matters here is that he’s leaping into the GOP War on Budgeting.

I’ve been talking about this for a while now: Republicans, for all their talk about deficits, don’t seem to assess their policy proposals as if changing revenues and spending has anything to do with federal budget deficits. Instead, their proposals make much more sense if you understand “deficit” as “stuff we don’t like.” So slashing taxes on the rich doesn’t, for Republicans, increase the deficit; it decreases it, because they don’t like taxes on the rich, and slashing them reduces something they don’t like.

What’s important to remember is that Romney’s position is totally consistent with supposed budget maven Paul Ryan, whose House budget last year had pretty much the same lack of detail on taxes. Of course, it’s also consistent with fantasy economics in which tax cuts – or at least the ones that Republicans want – will magically pay for themselves, no matter that even GOP hack economists aren’t willing to say that.

All in all, it’s no surprise that structural budget deficits soared when Ronald Reagan and George W. Bush entered the White House, and I fully expect the same result if Romney becomes president.