Once upon a time, a Latin American political party promised to help motorists save money on gasoline. How? By building highways that ran only downhill.

I’ve always liked that story, but the truth is that the party received hardly any votes. And that means that the joke is really on us. For these days one of America’s two great political parties routinely makes equally nonsensical promises. Never mind the war on terror, the party’s main concern seems to be the war on arithmetic. And this party has a better than even chance of retaking at least one house of Congress this November.

Banana republic, here we come.

On Thursday, House Republicans released their “Pledge to America,” supposedly outlining their policy agenda. In essence, what they say is, “Deficits are a terrible thing. Let’s make them much bigger.” The document repeatedly condemns federal debt  16 times, by my count. But the main substantive policy proposal is to make the Bush tax cuts permanent, which independent estimates say would add about $3.7 trillion to the debt over the next decade  about $700 billion more than the Obama administration’s tax proposals.

True, the document talks about the need to cut spending. But as far as I can see, there’s only one specific cut proposed  canceling the rest of the Troubled Asset Relief Program, which Republicans claim (implausibly) would save $16 billion. That’s less than half of 1 percent of the budget cost of those tax cuts. As for the rest, everything must be cut, in ways not specified  “except for common-sense exceptions for seniors, veterans, and our troops.” In other words, Social Security, Medicare and the defense budget are off-limits.