Seeking applause from a right-wing audience in Michigan, Mitt Romney vowed on Saturday: “I will cut spending, I will cap spending and I will finally balance the budget,” saying that he will end federal funding for all the usual Republican budgetary scapegoats — the Public Broadcasting System, the National Endowment for the Arts and the National Endowment for the Humanities. He has said much the same thing many times in recent months, hoping to woo the tea party extremists who keep rejecting his candidacy.

But Romney must think these “conservatives” very stupid if he’s promising to balance the federal budget by eliminating nominal amounts spent on the nation’s cultural programs. And he must think they’re even dumber if they believe he can do that while delivering the massive tax cuts and defense increases he has also promised. As a former corporate investor and state governor, he certainly knows that his numbers simply don’t work.

Or at least not in the foreseeable future, as the Committee for a Responsible Federal Budget explained in a study of Romney’s latest tax plan. Rather than bringing the budget into balance, as he has repeatedly promised, that plan would substantially increase the national debt over the coming decade by reducing taxes on people like Romney himself — the wealthiest 1 percent.

“Estimated roughly, ignoring interactions and microdynamic effects, we find that without offsets Gov. Romney’s plan on the whole would increase the debt by about $2.6 trillion,” according to the nonpartisan committee. The roughness of that estimate was unavoidable because Romney’s plan leaves out most of the vital details — such as which tax loopholes he would close and which vital programs and entitlements he would cut. It is full of tax cuts pleasing to gullible Republican audiences, but not much else.

So far, the hints that Romney has offered about proposed changes to the budget would increase rather than reduce deficits. Aside from his tax cuts — which represent an even bigger orgy of irresponsibility than the George W. Bush cuts — Romney often insists that he will substantially increase rather than reduce the defense budget, raising the total spent as a percentage of gross domestic product from 3.8 to 4 percent. That doesn’t sound like much until someone does the math, which results in an additional $40 billion or so annually. Again, there are few substantive details so far, except his promise to build another 15 Navy warships annually, at a cost of roughly $21 billion alone.

Eventually all the unbridled spending that Romney wants to enact on tax breaks for his rich donors and yet more Pentagon waste will add up to real money — unlike the cuts he has loudly aimed at the country’s cultural programs. Total annual spending on the National Endowment for the Arts, the National Endowment for the Humanities and the Corporation for Public Broadcasting — all hated by “conservatives” who behave like vandals intent on sacking the national heritage — amounts to less than $700 million, with an “m.”

In a national budget of nearly $4 trillion, with a “t,” $700 million is a truly meaningless amount, representing some minuscule fraction of military cost overruns. And Romney — our new Spartan leader who avoided the draft in France — surely knows that too.

So why does he talk about those cuts and avoid discussing the real tax increases and spending reductions that would be required to balance the budget? He seems to think that his tea party audiences can’t do simple arithmetic. He may well be right.

Joe Conason is the editor in chief of NationalMemo.com.