Michelle Obama last night described her husband's life as the "great American story" as she sought to portray him as someone who sympathised and understood the hopes and fears of ordinary Americans.

Michelle Obama last night described her husband's life as the "great American story" as she sought to portray him as someone who sympathised and understood the hopes and fears of ordinary Americans.

In an at times highly emotional address marking the high point of the first day of the Democratic National Convention, the 42-year-old lawyer, described her own working class upbringing in Chicago, declaring: "Barack and I were raised with so many of the same values, like you work hard for what you want in life, that your word is your bond. We treated people with dignity and respect even if we did not know them and even if we did not agree with them."

In a clear attempt at trying to convince voters that her husband was just as American as they were, Mrs Obama sought to press all the right buttons, talking about overcoming hardship through hard work, cherishing family values and showing compassion for others.

She name-checked senators Hillary Clinton and Joe Biden and spoke of how this week marked the 88th and 45th anniversaries respectively of when women got the vote and when Martin Luther King made his famous "I have a dream speech".

In a speech full of high rhetoric marked by a background of a cheering audience of some 20,000 people, the would-be First Lady spoke of the American dream and how her husband had lived it, noting how the son of a single mother from Hawaii could be on the verge of getting to the White House.

At times her address plunged into the sentimental as she held back tears and sniffed when she mentioned her late father. And at the end the resident convention band played Stevie Wonder's hit "Isn't She Lovely".

There was an added extra as Barack Obama himself - who in an earlier video suggested he had won his wife-to-be's heart by buying her an ice cream - popped up again on screen from Kansas, declaring: "Michelle you are unbelievable."

There was high emotion earlier in the evening when the 76-year-old Democratic icon, Senator Edward Kennedy, appeared on stage to a rousing reception. Recovering from treatment for a malignant brain tumour, the veteran looked frail but delivered his trademark booming oratory, declaring how this was "a season of hope" for an era of justice and fair prosperity with the election of Obama as president.

The Massaschusetts senator spoke of the future and said he means to be part of it, pledging to be at Obama's inauguration in January "when we begin the great test".

A video tribute covered his political life including his time with his brothers John and Robert. In words echoing his slain brother,the former president, he said that in November "the torch would be passed again to a new generation of Americans. The work begins anew. The hope rises again. And the dream lives on." Words that received a thunderous reception with the audience chanting: "Teddy, Teddy."

There had been strong doubts that Kennedy would even appear at the convention given his illness. However, he secretly flew to Denver on Sunday night, and his first stop was a hospital, where doctors examined him. His physicians had been wary of the convention appearance, especially his exposure to crowds, given the weakness of his immune system after weeks of chemotherapy and radiation treatments.

However, he insisted he would not want to be anywhere else and told the cheering crowd: "I have come here tonight to stand with you to change America, to restore its future, to rise to our best ideals, and to elect Barack Obama president of the United States."

Caroline Kennedy, who had earlier led the tribute to her uncle, said he "has been a senator for all who believe that the dream has never died." She said "Uncle Teddy" and Obama were "two men who have changed my life and the life of this country.

"Leaders like them come along rarely," she said. "But once or twice in a lifetime, they come along just when we need them the most. This is one of those moments."

Earlier, the day had been dominated by polls which suggested as many as one third of Hillary Clinton's supporters would vote for John McCain, the Republican presidential candidate, fearing Obama's inexperience and the prospect of higher taxes.

It emerged, following "face time", that Clinton and Obama had agreed to limit a divisive roll call for president, giving delegates a brief but historic choice between a black man and a white woman.

The deal would allow some states to cast votes for both Obama and Clinton before ending the roll call in acclamation for the Illinois senator. Clinton herself may cut off the vote and recommend unanimous nomination of Obama, according to Democratic officials involved in the negotiations. They discussed the deal on condition of anonymity while details were being finalised.

Some Clinton delegates said they were not interested in a compromise, raising the prospect of floor demonstrations that would underscore the split between Obama and Clinton Democrats.

"I don't care what she says," said Mary Boergers, a Maryland delegate who wants to cast a vote for Clinton.

As part of the deal, Obama aides circulated three petitions on the convention floor last night - supporting Clinton, Obama and vice presidential candidate Biden. Each needed 300 signatures to be nominated.

The dealmaking indicates the divided nature of the party: Obama does not have full control over a convention that includes many delegates who are enthusiastic Clinton supporters. But both senators have an incentive to help make peace between their opposing sides - Obama so he will have their backing in the November election and Clinton so she will be well positioned for a future run.

Clinton herself said she would not tell her backers how to vote but she told them she would cast her own vote for Obama. "We were not all on the same side as Democrats, but we are now," she said.

Kathleen Kennedy Townsend, the eldest child of the late Bobby Kennedy and a former lieutenant governor of Maryland, said the animosity that some Clinton delegates felt towards Obama "is getting worse."

Townsend, a Maryland delegate, was a strong Clinton supporter but now is fully behind Obama. She said she partly understood why some of her colleagues had not joined her yet. "There's a moment that you want to enjoy your bitterness," she added.