Driving home Thursday evening, I tuned the radio to WCSP-FM — Washington’s C-SPAN station — in time to hear Nancy Pelosi introduce President Obama for his address to the House Democratic Caucus, gathered in Williamsburg, Virginia.

The president’s speech was a real humdinger. Even his harshest critics will credit Barack Obama for being a tremendous orator. Put him in front of a TelePrompter with a good text, and the man’s sonorous baritone works wonders. For this power, his speechwriters can claim no credit. He could read the ingredients from the side panel of a box of pancake batter (“…dextrose, partially hydrogenated soybean oil with mono- and diglycerides…“) and inspire standing ovations from an audience of adoring Democrats.

The deployment of Obama’s awesome oratorical power almost immediately produced its intended effect, intimidating enough spineless Senate Republicans to gain an unprincipled compromise over the massive “stimulus” bill that the president told us Thursday is the only alternative to economic catastrophe.

Announcing the compromise Friday evening, Sen. Arlen Specter of Pennsylvania said: “I think no one could argue with the fact that the situation would be much worse without this bill.”

Really, Senator? “No one could argue”? Many certainly will argue with you, especially with your apparent assumption that “this bill” is the only possible response to the current economic crisis, and that we must either pass “this bill” or suffer the catastrophe about which the president has so direly warned.

The real problem with the stimulus bill is not that it is too big (although it is too big) nor its various objectionable ingredients (although many are objectionable), but rather that it is based on a false economic theory.

“The American people…did not vote for the false theories of the past,” Obama assured his listeners Thursday. Yet the “economic recovery plan” pushed by Pelosi and other Democrats is nothing but Keynesian theory in postmodern drag, elegantly costumed by the Orator-in-Chief with a lot of glittering generalities about “modernizing our health care system…21st century classrooms…and end[ing] the tyranny of oil in our time.”

This plan is not a Change We Can Believe In and, as I wrote two months ago, before Obama was inaugurated, it won’t work.

No amount of presidential persuasion, nor any conceivable quantity of federal spending, can repeal the basic economic law of supply and demand. Thus, if Congress should enact this idiotic “stimulus” — a neo-Keynesian pump-priming venture absurdly overbalanced to the demand side of the equation — nothing is more predictable than its failure to spur real recovery. Indeed, the Pelosi plan is so close to being the exact opposite of what our economy needs at this juncture, many informed observers do not hesitate to say that it will actually delay recovery and perhaps make the recession far worse than it already is.

Obama and other Democrats have repeatedly invoked the idea of an expert consensus in favor of the Pelosi plan. In his Jan. 3 weekly radio address as president-elect, Obama said that “economists from across the political spectrum agree” in support of the plan, and in a Jan. 9 press conference, he declared: “There is no disagreement that we need action by our government — a recovery plan that will help to jump-start the economy.”

Tired of hearing this insipid “everybody agrees” argument, the libertarian Cato Institute produced an open-letter response ad (pdf) featuring the bold headline: “With all due respect, Mr. President, that’s not true.” The open letter has now been signed by more than 200 economists, and I overheard a top Cato official last week tell a supporter that the institute plans to continue its ad campaign against the phony Keynesian consensus.

Assuming that such efforts can put enough spine into the GOP’s jellyfish caucus to stop the “stimulus” from being rushed into law, so that Congress is forced to go back to the drawing board, what then? If political pressure to “do something” cannot be resisted, what should be done, especially by those few Republicans still determined to preserve some semblance of economic freedom in America?

First of all, Republicans ought to demand disassembly of the “stimulus” package into reasonably specific chunks, so that Democrats cannot claim that all opposition is “anti-recovery” or “anti-progress.”

Second, Republicans need to address the fundamental dishonesty of the rhetoric used by stimulus supporters. Obama, Pelosi and other Democrats never miss a chance to talk about the need for building infrastructure — “our nation’s crumbling roads and bridges,” etc. — even though barely 3 percent of their original $900 billion plan was targeted for such construction. If Pelosi wants to bring forward a highway construction bill as a sort of emergency jobs program, let her do so, and stop misleading Americans as to what’s really in her omnibus stimulus scam.

Third, Republicans could reasonably argue for additional defense spending as a form of economic stimulus. Our armed forces have been frayed by extended deployments in Iraq and Afghanistan. Higher military pay, expanded incentives for recruitment and re-enlistment, more money for equipment renovation and repair — these are legitimate expenditures that would pump cash into the economy. If Congress is determined to start throwing around hundreds of billions of dollars, surely the lobbyists for Lockheed Martin, Northrop Grumman and other defense contractors can suggest projects that would create high-paying private-sector employment in the aviation and ship-building industries.

Fourth and finally, Republicans should consult some of the economists who’ve signed that Cato open letter and develop some smart arguments against the underlying Keynesian rationale of stimulus spending. It is never a bad time for Republicans to speak economic truth, and the truth about the Pelosi plan can still be summed up in three words: It won’t work.