Nick Coleman: Ad hominem, ad infinitum: Good grief.

By this point, Americans who voted for Barack Obama in 2008 are used to being called socialists, especially if they still support the beleaguered president who came to the White House at a time of two wars, financial collapse, rising joblessness and all the rest of the bitter legacy of eight years' misrule by George W. Bush and Co.

We've heard the socialist slur repeatedly from such brilliant students of history as Rush Limbaugh, Glenn Beck, Michele Bachmann (Minnesota's Poster Girl for Why We Need High School Civics Classes) and that pinnacle of wit and wisdom, Sean Hannity, who is the kind of Irishman my people used to refer to as "Blueshirts."

Hannity tried and failed to get former Vice President Dick Cheney to call Obama a socialist last week. Cheney said he was "deeply disturbed" by Obama's foreign policy but refused the bait when Hannity asked if Obama was a socialist. "I don't want to use that kind of label," Cheney said.

When Dick Cheney comes off as conciliatory, we are moving into dangerous waters. Nothing is too vile, too preposterous or too paranoid to be said about Barack Obama.

The mayor of one Nashville suburb claimed last week that our "Muslim president" (Obama is not a Muslim) delivered his Afghanistan plan on Dec. 1 deliberately in order to preempt the annual broadcast of "A Charlie Brown Christmas." I, too, was annoyed by the preemption. But a real Muslim America-hater would have been smarter to preempt Barbara Walters' "Most Fascinating People of 2009" special. Of course, Barbara has been playing this game a long time, and she is no dummy: She named Michelle Obama the very most fascinating person of the year.

Sorry, Charlie.

I also heard a "Tea Party" supporter on radio claiming that you can tell Obama hates America just by looking at him. All I can tell by looking at him is that his skin color is different than that of every other president. Maybe that's what the Tea Party person meant.

Health care reform? A meaningful jobs program? An effective plan to save millions of middle-class homeowners from foreclosure? A revised war strategy that doesn't risk thousands of lives and billions in treasure to control a lawless country of minimal strategic importance? A commitment to fighting global warming?

Almost all of the Obama agenda that received almost 70 million votes 13 months ago has run headlong into a wall spray-painted with "socialism" graffiti. The socialism standoff is so deep now that Democratic leaders in the Senate, after achieving agreement on health care reform, were reluctant to reveal details of the plan. The only thing known for sure, at this writing, is that, whatever the details, it will be denounced as a conspiracy on the part of a socialist elite that doesn't want to let Americans enjoy their God-given right to live with unaffordable, inaccessible health care or go bankrupt trying to buy it while the insurance companies get fat.

This polarized paralysis is the result of a political strain of "denialism," the theory (put forth in a book by the same title written by Michael Specter) that we have arrived at a point where facts, science and intelligent discussion no longer matter. Fear, prejudice and ignorance can prevail. And name-calling is their weapon.

Well, two can play at that game. So let me say it's not "socialists" who have brought the country to paralysis. It's the "Marxists."

As in Groucho, Chico and Zeppo.

"I don't know what they have to say," he sings. "It makes no difference anyway. Whatever it is, I'm against it! ... Your proposition may be good, but let's have one thing understood. Whatever it is, I'm against it!"

Like many entertainers, Groucho was accused of being a Communist, and J. Edgar Hoover's G-Men scrutinized every joke he delivered in a vain attempt to detect Communist tendencies when he was host of the quiz show "You Bet Your Life."

That's the show where a duck would fall from the ceiling, carrying a card in its Groucho-like beak that displayed the "secret word." Today's secret word: socialist.

It's not funny, but it's working. Those who oppose Obama don't care what he offers or whether it's a good idea. They're against it.

A man who would keep Charlie Brown off the air? Gotta be a socialist.