Mr McCain wrapped up the Republican nomination in March, giving him a three-month head-start on whoever was going to be his Democrat opponent. But no one was much interested in him while Mrs Clinton and Mr Obama were still slugging it out.

She was casting doubt on her opponent’s capacity to lead America and her victory in Ohio showed that Mr Obama was struggling to win over white voters in the blue-collared rust belt and red-necked Appalachia, while her (albeit narrow) victory in Texas meant that she still had a slim chance of securing the nomination. It all depended on the super-delegates.

Her cause was helped by an unexpected source: the man who conducted Mr Obama’s marriage ceremony, baptised his children and gave him the title of his second book, The Audacity of Hope. Footage of the Rev Jeremiah Wright, Mr Obama’s pastor in Chicago for nearly 20 years, delivering incendiary sermons exploded on to television screens. In one, filmed a week after the September 11, 2001 terrorist attacks, he declared: “God damn America!”

It was a potential disaster for Mr Obama, one that fed into doubts about his race, patriotism and values. Many voters believed the senator was a secret Muslim.

Mr Obama at first tried to defend Mr Wright, explaining in a speech on March 18 that the pastor was from a different generation. “I can no more disown him than I can my white grandmother.” Finally Mr Obama disowned him.

Mrs Clinton had problems of her own. She twice told rallies how, as First Lady, she landed in Bosnia and dashed from an aircraft under sniper fire. Video footage showed this to be absurd. She shrugged and fought on with a more aggressive campaign. Mr Obama was overwhelmed by 10 points on April 22 in the last big primary, Pennsylvania, then suffered defeats in Kentucky and West Virginia.

Mrs Clinton conceded on June 6. Mr Obama limped over the finishing line having suffered a string of defeats and with a divided party, far from assured of victory.

Jeremiah Wright: the man

The black liberationist pastor of the Trinity United Church of Christ in Chicago’s South Side proved to be the thorn in Barack Obama’s side.

The two met in the late Eighties when Mr Obama moved from New York to be a community organiser in Chicago’s poor neighbourhoods. Mr Obama was spiritually adrift but warmed to Mr Wright’s Afrocentric theology. In 1988 he was brought to tears by his sermon, The Audacity of Hope, and later used the title for his second book.

Over the next few years Mr Wright would officiate at Mr Obama’s wedding and baptise his children. The two appeared close until the strain of the election campaign broke the ties between them. Mr Wright was always prone to inflammatory remarks but it was his declaration “God damn America” after the September 11, 2001 attacks that was his undoing.

Video clips of the sermon were viewed millions of times over the internet and ultimately forced Mr Obama to disown him. While some on the Right attempted to make Mr Wright an issue, John McCain declared him off-limits, making it difficult for the Republicans to resurrect the issue.

Obama defuses Wright row

"I have already condemned, in unequivocal terms, the statements of Reverend Wright that have caused such controversy. . .

As imperfect as he may be, [Reverend Wright] has been like family to me. I can no more disown him than I can disown the black community. I can no more disown him than I can my white grandmother – a woman who helped raise me, a woman who sacrificed again and again for me, a woman who loves me as much as she loves anything in this world, but a woman who once confessed her fear of black men who passed by her on the street, and who on more than one occasion has uttered racial or ethnic stereotypes that made me cringe.

These people are a part of me. And they are a part of America, this country that I love."

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