The Tax Policy Center came out with a report yesterday confirming its earlier study: Mitt Romney’s tax plan is either impossible or would raise taxes on middle-class taxpayers.

Once again, that’s because the specific commitments Romney has made just don’t add up. Remember, Romney has called for revenue-neutral tax reform that would cut rates by 20 percent while retaining and, in some cases, adding to current expenditures that he counts as “incentives for saving and investment” and eliminating the estate and alternate minimum taxes. The problem is that there just aren’t enough deductions, exclusions and credits remaining to make up the revenue lost just from the rich.

What’s striking about all of this is that there’s a perfectly reasonable out for Romney that he hasn’t taken and that I suspect he won’t take no matter how hard he’s pressed. All he has to do is to say that his top priority is to make sure that no one below a certain income level would pay more in his plan and that to make that work he would be flexible in his other goals.

In particular, he could say that if his plan doesn’t add up while cutting rates by 20 percent, then he would cut the rates by a smaller amount to make it all work out.

That’s it.

Mitt Romney says that, and the whole issue goes away. All of a sudden, instead of a threat to raise middle-class taxes, Romney would be simply be an advocate of the widely approved idea of lower rates and fewer loopholes, end of story. Sure, he still wouldn’t be detailing the specific tax expenditures that he opposes, but he’d be supplying workable priorities for how to proceed when trade-offs are necessary. It would shoot down the entire Tax Policy Center line or criticism.

And yet, Romney won’t do it.

The obvious conclusion is that the priorities in his plan are the specific rate cuts and tax advantages for upper-income filers. They are not about protecting the middle-class, and they certainly are not revenue neutrality. Indeed, the obvious conclusion is that those are the ultimate priorities for the Republican Party, and Romney has the nomination only on the condition that he will back massive tax cuts for the rich. The same condition, that is, that got George W. Bush the nomination.

But again, the tip-off here is that Romney could easily defuse this entire issue, and yet he won’t do it. It’s about as clear an indication that you can get about the real, absolute priority for today’s Republican Party: Whatever else, more tax cuts for rich folks.