Smear tactics are a routine part of the American political armoury and, last year, barely a day went by without the US Democratic presidential contender from Illinois being referred to as Barack Osama (writes Jenny Booth).

Barack Hussein Obama may have thought he had weathered the right-wing onslaught. Yesterday, however, there a return to the bad old days, although it seems that the incident was more a slip of the tongue than yet another attempt to write him off as a dangerous, Muslim-sounding al-Qaeda sympathiser.

The culprit was Dean Singleton, a publisher who, as founder of the NewsMedia newspaper group and chairman of the board of the Associated Press news agency, was eager to hear more about the senator's foreign policy ideas.

"Can you imagine shifting a substantial number (of US troops from Iraq) to Afghanistan where the Taleban has been gaining strength and Obama Bin Laden is still at large?" Mr Singleton asked his guest speaker at the AP annual lunch in Washington.

Senator Obama cast him a wry look and said, "I think that was Osama bin Laden" - prompting Mr Singleton to collapse in confusion.

Clutching his head, he stammered: "If I did that, I'm so sorry."

The candidate then smoothed over the gaffe, to the relief of the audience of 1,200 news executives and TV cameras which had collectively sucked in its breath. “No, no, this is part of the exercise I’ve been going through for the last 15 months,” Senator Obama said. “Which is why it’s pretty impressive that I’m still standing here.”

There was laughter and a round of applause.

Senator Obama was warned at the time of 9/11 not to attempt a political career because of his menacing-sounding name, and has been fighting attempts to link him with al-Qaeda for months. A typical incident occurred last November when Mitt Romney, the since-defeated Republican candidate, launched a critique of Democrats' foreign policy in the same week that the real Osama bin Laden had released an audio tape calling on radical Muslims to fight the Americans in Iraq.

"Actually, just look at what Osam — uh — Barack Obama, said just yesterday," said Mr Romney. "Barack Obama calling on radicals, jihadists of all different types, to come together in Iraq."

Romney aides dismissed it as an accidental slip, but Senator Obama said he did not believe it was an accident, and warned that Republicans would try to "make me into this foreign, clearly black person, and to scare you".

Answering a question about negative campaigning, he tried to make light of the incident, saying: "I have a lot of trouble growing a beard, and he lives in a cave."

The incidents have persisted, not all of them deliberate. The CNN news channel was forced to apologise after it broadcast a story about the hunt for the al-Qaeda leader under the headline "Where's Obama?"

Untrue claims that Senator Obama had attended a radical Islamic madrassa school as a boy in Indonesia spread like a virus through the media and internet.

One entrepreneur even tried to make money out of the association. Alexander Batile, a Florida businessman, was eventually blocked by the US authorities from trademarking the name “Obama bin Laden” which he had intended to use on a T-shirt which featured Senator Obama in a turban with an assault rifle next to Hillary Clinton leashed like a dog and wearing a burka.

The son of a Kenyan father and white American mother, Senator Obama is selective in the way he refers to his background, aware that he must present himself as a candidate for voters of all types. But the fact that he is a person of colour is an important part of his message of change.

"The day I am inaugurated, the country will look at itself differently, but perhaps more important the world will look at America differently," he told audiences after the Romney attack.

He has tried to cast his background in a light that conservative white US voters may find easier to accept. Having a grandmother in a "little African village with no water or electricity" would give him more credibility with African leaders when it came to discussing both aid and the need to tackle corruption, he said.

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