When presenting hundreds of billions of dollars in tax cuts this week, John McCain and his campaign said the cuts wouldn't necessarily worsen the deficit. The key, they said, is McCain's commitment to cutting spending by eliminating congressional earmarks.

On its face, the claim is simply foolish. Even if McCain could eliminate the entire practice of placing earmarks in spending bills -- a dubious proposition -- Taxpayers for Common Sense did an exhaustive review of the 2008 expenditures and found $18.3 billion in earmarks. With McCain's tax cuts poised to cost about 22 times that much, the "solution" isn't exactly budget neutral.

But this gets even more entertaining when we take a closer look at what's included among the earmarks McCain plans to eliminate.

Sen. John McCain (R-AZ) has long portrayed himself as a staunch supporter of Israel. "Obviously," McCain has said, "I have been a very strong proponent to the State of Israel." He recently told the Jewish Journal that if elected president, he would "hit the ground running" and immediately get involved in the Israeli-Palestinian peace process. It is astounding then that McCain has essentially vowed to eliminate U.S. funding assistance for Israel.

As it turns out, McCain economic adviser Douglas Holtz-Eakin said McCain, if elected, would eliminate earmarks based on the definition used by the Congressional Research Service. And that includes, among other things, "economic and military aid to Israel."

Confronted with the implications of McCain's proposal, his campaign said earmarked aid to Israel wouldn't count.

It's a reminder of why it's difficult to take McCain seriously on matters of public policy. Pressed for details on what he believes, McCain a) loves vague generalities; b) gets easily confused; or c) decides his commitments are a lot more flexible than he'd like us to believe.

As for earmarks, he's embraced a simplistic maxim: earmarks = waste. Confronted with evidence to the contrary, his opposition wanes. But therein lies the point -- every earmark has a purpose and supporters who can defend it.

Where will McCain draw the line? He doesn't know. How much will it save? He doesn't know. When can we expect more concrete answers? He doesn't know.

Post Script: Just as an aside, if Dems really wanted to be aggressive, for the rest of the year, they'd argue, "McCain said, if elected, he would cut off aid to Israel, but later changed his mind." Just sayin'.