What has happened to Barack Obama?

He was the candidate with everything . . . youthful, gifted, charismatic, with a message of national unity, who had even had the prescience to speak out beforehand against the disastrous and now highly unpopular war in Iraq.

And yet Hillary Clinton's lead in the race for the Democratic nomination grows by the week. Obama is too inexperienced, some say. He doesn't have a coherent message, it is argued. Others believe that he has simply been outmanoeuvred at every turn by Hillary's battle-tested and ruthless team.

But there may be another reason. Perhaps it's because he's stopped wearing his American flag pin and has subconsciously been cast by the electorate into that dark pit reserved for those deemed unpatriotic.

You know the pins I mean . . . the little stars and stripes badge worn unfailingly by George Bush and his top officials. They came into vogue after 9/11 as, reasonably enough, a symbol of of national solidarity after the trauma of the terrorist attacks.

At one point, in the first flush of the BlairBush alliance, you could even find double pins, combining the British and American flags. These never caught on. Outside of international sporting contests, the British were wary of flaunting their patriotism long before Bush became one of the least-loved politicians on the planet.

Not so the Americans. For Bush and many other politicians, the tiny flag became part of their uniform, along with the dark suit, crisp white shirt and precisely knotted tie.

For foreigners, the pin might have been a statement of the blindingly obvious . . . everyone knows only too well that Bush is American and that, as President, he defends what he sees as the American national interest.

But it also became tacit emblem of the Bush doctrine in the "war on terror" unleashed by 9/11. Either you're with us or against us.

Wear the pin, and there can be no doubt where you stand.

Then one day on the campaign trail in Iowa this month, a sharp-eyed reporter noticed Obama was not wearing his pin and asked why. The candidate could have brushed the question aside with a smile or a joke, making the point that he had no need to prove his patriotism. Instead Obama committed the classic political gaffe. He gave an honest and frank answer to a question.

"You know, the truth is that right after 9/11 I had a pin. But shortly after 9/11, particularly as we're talking about the Iraq war, that [the pin] became a substitute, I think, for true patriotism, which is speaking out on issues that are of importance to national security.

I've decided I won't wear that pin on my chest. Instead I'm gonna try to tell the American people what I believe will make this country great, and hopefully that will be a testimony to my patriotism."

Predictably, right-wing commentators went purple. "Why do we wear pins?

Because our country's under attack, " opined Sean Hannity on Fox News. (I thought it was Iraq that's under attack, but never mind). But moderates, too, wondered whether Obama was implying his "true patriotism, " as demonstrated by his opposition to the war, was superior to the patriotism of ordinary Joes who wore the pin, or drove their gas guzzling cars with American flags streaming in the wind?

Only in America, surely, could you have a debate like this. But in US politics, patriotism is not only the cheapest card to play. It is by far the most effective.

Lapel pins are one thing. But since 9/11 the Bush administration has wrapped itself in the flag, as it rode roughshod over the constitution to extend its executive power and steamroller the Democrats into submission.

Not until November 2006, when voters handed control of Congress back to the Democrats, did the worm start to turn. But despite the mess in Iraq, the basic strategy still works. Witness the continuing Democratic cave-ins on Capitol Hill, on torture, warrantless wiretapping, and continued funding for the war. Democratic leaders huff and puff. But the White House then accuses opponents of being "unpatriotic, " and invariably gets what it wants.

No-one has grasped the lesson more thoroughly than Hillary, as she seeks to quell doubts she has the right stuff for commander-in-chief. After voting for the Iraq war in 2002, she recently backed a Senate resolution on Iran that some fear will be interpreted by the White House as carte blanche for the use of military force against Tehran. Lest we forget, she often wears the flag pin.

And the patriotism card, having served Bush so admirably, could decide the Republican race as well.

Quite possibly, it will carry twicedivorced Rudy Giuliani to the nomination in 2008 . . . even though he is pro-choice on abortion and supports gay rights and gun control, to the dismay of social conservatives so important in primaries. But the man who was mayor of New York at the time of 9/11 talks tougher than anyone on terrorists, national security and going after Iran. Needless to say, he's never seen without a flag pin.

The odd thing is that, in my experience, Americans in most other ways are not 'my country right or wrong' patriots. They are understandably proud of America's astounding achievements. But they acknowledge that some things are done better abroad.

They readily admit the failings of the US health care system. They worry about the growing gulf between rich and poor, and are appalled by instances of racial injustice.

Even 9/11 didn't produce a sea change in their feelings. A 1999 Gallup poll for instance found that 21% of Americans saw themselves as "extremely patriotic". In January 2002, just four months after the attacks, the figure had risen only marginally, to 24%.

But America's flag is different. No country reveres it as much and no country displays it as much. No other country has an elaborate etiquette entirely devoted to its flag.

No sporting event is complete without it even though all participants are American.

Be it the World Series decider or a high school football game, the flag flies over proceedings and the national anthem is played.

I once forgot to remove my hat for the Star Spangled Banner at a minor league baseball game in Ohio. "You're supposed to take it off, " said a man nearby, in somewhat threatening tones. I wanted to reply along the lines of "I'm not American and anyway, isn't this a free country?" But I quickly thought better of it.

You don't mess with US patriotism.

Now Obama may have done precisely that. He was right on Iraq then. He is right now to insist that the last thing the country needs is unquestioning assent to the foreign policy of its leaders, and that dissent is an ingredient of "true patriotism". But his frankness could cost him the nomination.