On the eve of the nine-month anniversary of Barack Obama's election, America and US politics is, fittingly enough, obsessing about the president's birth, and specifically his birthplace.

The gestation period for any conspiracy theory is far longer than that for human infants, of course, or even elephants. It tends, in fact, to be endless. It is 45 years since JFK was murdered, 40 since the first moon walk, and almost eight since the twin towers fell, and while the various notions (second gunman, studio mock-up, Mossad plot) were conceived almost immediately after those events, they have yet to deliver anything more substantial than lovingly nurtured insanity.

That rag-tag coalition of shock jocks, publicity-hungry attorneys, the credulous and simple-minded, plain nutters and above all frustrated racists collectively known as "the birthers" have spent a year banging on about Obama's arrival in this world, and their successors will be banging on about it long after he's left it for the next.

With the hissing wrath of those struggling ferociously to repress the volcanic pressure to screech "uppity nigger" at their head of state, these people conveniently conclude that Obama isn't their head of state at all. The second article of the US constitution dictates that "no person except a natural born citizen" can be president, and the birthers argue that since Obama was born in Mombasa, Kenya, he is disqualified.

One army officer, a Major Stefan Cook, refuses to serve in Afghanistan on the grounds that, since Obama isn't rightfully his commander-in-chief, the order to deploy is illegal. As for his lawyer, her sobriquet is Queen Bee of Birferstan, and the on-screen mini-biog accompanying a recent appearance on CNN briefly imbued that sober channel with Springeresque exoticism. "Dr Orly Taitz," it ran. "CA attorney. Dentist. Real estate broker." As the sublime Jon Stewart pointed out, if you're contemplating a scam whereby a lawyer wins you enough in damages for botched root-canal work to buy the home of your dreams, here's your gal.

Were it just Orly, whose legal qualification was earned over the internet, and a smattering of fellow narcissist-fantasists, the whole thing might be dismissed as touching idiocy. After all, if people wish to think that the August 1961 certificate of live birth is a forgery despite verification from Hawaiian officials, the state's Republican governor and independent body factcheck.org; if they want to believe that birth announcements were planted in local Honolulu papers solely to prepare the ground for the day he could illegally enter the US and start his Islamist sleeper march on the White House; if they choose to trust a carefully edited interview with his Kenyan step-grandmother, cut off before she repeatedly confirms that he was born in Hawaii – well, that's their absolute right. Many of us solemnly believe objective absurdities. I believe that Tottenham Hotspur is one of the world's great football clubs, for instance.

What is most intriguing about the birther "movement" is the light it casts on the necrotic state of the American right. Who leads them at the minute is a mystery. Some think it's Sarah Palin, others the deliriously repugnant Rush Limbaugh, who inevitably joins the other oracles of US radio and TV in keeping the birther debate bubbling. What leadership there is, so it seems to this ignorant observer, comes from the grass roots – the sort of God fearin', gun-totin', sister-shaggin' sweethearts who screeched "terrorist" and "kill him" when John McCain mentioned Obama on the stump. Unable to compute that America elected a black man, they have decided that he isn't their president at all. No longer can they use the 'n' word or fantasise publicly about lynch mobs. But they can divert their rage into a bogus legalistic dispute, rejected time and again by the Supreme Court, as freely as they like.

And their elected representatives follow them in dumb terror. A Huffington Post reporter approached a clutch of Republican congressmen on Capitol Hill last week to ask if they think Obama was born on US soil. Several scurried away without replying. Another spent 20 minutes pretending to examine CDs in a shop to avoid the question. The only one prepared to answer said that Obama was a natural-born citizen "so far as I'm aware" – an echo of Hillary Clinton doing her genteel bit to foster the myth about him being a Muslim sleeper during the primaries by referring to him as a Christian "so far as I know".

As Obama suggested after the arrest of the esteemed Harvard professor Skip Gates in his own Washington home, his election was not the magical cure-all some hoped. But then racism is stubbornly resistant to silver bullets. These things take time. How much is anyone's guess, but America is waking to the realisation that untold millions aren't even close to accepting the democratic will that put a black man in the White House. Most will kid themselves that their objection is constitutional rather than racial, and a few will be emboldened to hatch plots to uphold their patriotic ideals via an assassin's gun.

The Prez, meanwhile, is content to deal with such banalities as healthcare reform, and stay silent on the question of his birthplace. Politically speaking, this is a gift from heaven, exposing the vicious dementia of the Republican right to a degree of riducule that should help sweep him to a second term.

Shane Coleman is on leave