While national security issues have gobbled up most news space over the past week, a couple of harsh analyses of John McCain’s economic plan have sailed under the radar.

The Center for American Progress Action Fund* released a study yesterday concluding that McCain’s plan would create a cumulative debt of $12.7 trillion by 2017—the highest debt since 1951. Corporate tax cuts, a repeal of the Alternative Minimum Tax, and an extension of the Bush tax cuts—all staples of the McCain plan—would cost significantly more than the senator’s proposed earmarks cuts and discretionary spending freeze would provide, the study argues. (PDF here .)

Also this week, calls McCain’s suggestion that he can balance the budget while extending Bush’s tax cuts “dubious at best.” The main problem: Getting rid of earmarks doesn’t mean the money won’t get spent. It just means it doesn’t happen in the form of earmarks. As the writers phrase it, “earmarks often simply tell agencies how to spend money that they are already getting.” And when it comes to discretionary spending, McCain hasn’t detailed what areas he would cut. He says he would exempt military spending, so that’s out. And because the nondefense budget is only $540 billion, he would still have to convince Congress to “slash 18.5 percent of the funding for everything else in the discretionary budget— things like veterans’ health benefits, highway construction, elementary and secondary education, and immigration services.”

McCain’s economic plan has its defenders . But neither they nor the McCain campaign has produced numbers to back up the budget-balancing claims. (At least not that I’ve seen.) The argument seems to be that cutting taxes raises revenues, but even McCain’s own senior policy adviser has rejected that claim in the past. Spokesman Brian Rogers dismissed the CAP study as coming from “a left-wing Democratic front group” but did not provide alternative figures. “The fact that they falsely criticize Sen. McCain’s policy proposals is unfortunate, but it’s hardly surprising,” he wrote in an e-mail.

* Clarification: We originally credited the Center for American Progress. In fact, it’s the Action Fund, the center’s 501(c)(4) sister affiliate, that published the report.