Smash hit

But Robert Johnson, the founder of Black Entertainment Television and a leading supporter of Mrs Clinton, was calling for Congressmen to lobby Mr Obama and tell him to make her his vice-presidential nominee. He said Mrs Clinton has authorised him to make the case that she should be the running mate for her former rival.

A poll released this week by the Pew Research Centre found that 76 per cent of Clinton voters would like to see Mr Obama choose her - up from 69 per cent in March - but 54 per cent of his supporters were opposed to the idea, an eight per cent increase.

Mr Obama's campaign is known to be sceptical about sharing a ticket with Mrs Clinton. There were reports last night suggesting Bill Clinton's secretive financial dealings would be a significant barrier to her getting the vice-presidential slot.

The nominee-elect himself announced yesterday that he had appointed a panel, including Caroline Kennedy - the daughter of the assassinated president - to begin sifting through possible candidates for the post. Last night, appearing at two fund-raisers in Mrs Clinton's New York backyard, he promised merely to "look at a whole range of options".

Mrs Clinton's speech on Tuesday appears to have hardened opposition to her being the vice-presidential nominee, with many Obama supporters complaining that she had spoilt his big night.

James Clyburn, the House of Representatives majority whip and the most senior African American on Capitol Hill, said: "At some point, she needs to congratulate the man for having won. Those kinds of things are important to us who grew up in the South with these kinds of slights. That speech cannot be seen as anything but a slight."

Mr Obama yesterday strode on to the international stage for the first time as the Democratic Party’s presidential nominee-elect and vowed to use “all elements of American power” to eliminate Iran’s nuclear threat. In his toughest speech yet on the subject, he declared: “I will do everything in my power to prevent Iran from obtaining a nuclear weapon. Everything."

His address to the American Israel Public Affairs Committee was designed to counter Republican claims that that his foreign policy is soft and naive. Mrs Clinton has, in the past, expressed similar sentiments. But yesterday, perhaps rehearsing for the role of playing second fiddle to Mr Obama, she spoke from the same podium to assure the audience: "I know Senator Obama will be a good friend to Israel".

Later she visited her campaign's headquarters in Arlington, Virginia, where she told staff told they would be paid through to June 15 but that tomorrow would be their last day of work.

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