Michelle Obama, wife of Democratic presidential candidate, Sen. Barack Obama, D-Ill., and daughters Malia, 10, left, and Sasha, 7, wave to the crowd after her speech at the Democratic National Convention in Denver, Monday, Aug. 25, 2008. (AP Photo/Ron Edmonds)

DENVER (AP) _ Michelle Obama spoke of love of family and country — a bookend speech to one by an ailing but impassioned Sen. Edward Kennedy — as Democrats convened to nominate Barack Obama and pass the torch to a candidate who would be the first African-American president.

With Republican opponent John McCain drawing even in a presidential contest marked by a nasty back-and-forth of television attack ads, the Democrats on Monday crafted a seamless opening of their four-day national convention, the symbolic start of a historic two-month campaign for the White House.

The convention offers a chance to heal wounds opened in Obama's bruising battle with Hillary Rodham Clinton and reassure voters still wary of putting a political newcomer in the White House

Michelle Obama, who has come under attack by Republicans trying to paint her as an unpatriotic radical, sought to turn the tables on her critics, telling a cheering crowd in Denver's Pepsi Center: "We have an obligation to fight for the world as it should be.

"That is the thread that connects our hearts. That is the thread that runs through my journey and Barack's journey and so many other improbable journeys that have brought us here tonight, where the current of history meets this new tide of hope.

"That is why I love this country."

She said her husband would bring "the change we need," and she pledged he would end the war in Iraq, revive a sputtering economy and extend health care to all.

Kennedy, who is battling brain cancer, strode strongly to the lectern in an appearance that was not expected just days ago. The crowd came to its feet with a roar waving thousands of blue signs as he was introduced by his niece, Caroline Kennedy Schlossberg — the only surviving child of the slain President John F. Kennedy.

The scion of an American liberal political dynasty wagged his finger and said in a strong voice:

"Barack Obama will close the book on the old politics of race and gender and group against group and straight against gay.

"And Barack Obama will be a commander in chief who understands that young Americans in uniform must never be committed to a mistake, but always for a mission worthy of their bravery."

The Massachusetts elder statesman vowed to be on hand in January for the next presidential inauguration and concluded with a rousing reprise of a speech he gave at the 1980 convention.

"This November the torch will be passed again to a new generation of Americans, so with Barack Obama and for you and for me, our country will be committed to his cause. The work begins anew. The hope rises again. And the dream lives on."

Kennedy and Obama's wife were the bookends of an evening that left the delegates cheering, one representing the party's past, the other its future.

Michelle Obama, eager to counter a Republican claim that her husband is an elitist, said his story is classically American, his family one that scrimped and saved "so he could have opportunities they never had themselves." Obama was largely raised by grandparents after his parents, a white woman from Kansas and a black man from Kenya, divorced.

Among his values, she said: "that you work hard for what you want in life, that your word is your bond and you do what you say you're going to do, that you treat people with dignity and respect, even if you don't know them, and even if you don't agree with them."

The first night of the convention concluded with Michelle Obama and her daughters Malia,10, and Sasha, 7, on stage, talking to the candidate over a satellite link from a family's home in Kansas City, Missouri, where he had watched his wife tell their family story.

Behind the scenes, Obama's representatives reached an agreement with former rival Hillary Rodham Clinton's camp to limit a divisive roll call for president, giving delegates a brief but historic choice between a black man and 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 finalized.

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.

Michelle Obama included a tribute to her husband's former rival, crediting Clinton with having placed "18 million cracks in the glass ceiling" that constrains women's ambitions.

Kennedy's speech was an implicit appeal to Clinton's delegates — and the 18 million voters who supported her in the primaries — to swing behind Obama.

He said the country can meet its challenges with Obama as president. "Yes we can, yes we will," he said, echoing Obama's own signature refrain.

Though Clinton has asked her supporters to back Obama, a new poll showed nearly 30 percent of her backers would not. The leader in the House of Representatives, Speaker Nancy Pelosi, acknowledged that her fellow Democrats "had not yet achieved the complete reconciliation that we need."

Obama stunned the U.S. political establishment by defeating Clinton, arguably the most powerful name in Democratic politics. Through a drawn-out primary campaign, he shattered fundraising records, running on a message of hope and change.

But Obama, a 47-year-old first-term senator, has struggled to win the support of white working-class voters, many of whom supported Clinton and could be pivotal in the November election. Some doubt that he has the experience to lead the nation. He has also had to fend off challenges to his patriotism and unfounded rumors that he is a Muslim.

"There are people who are not going to vote for him because he's black," said James Hoffa, president of the Teamsters union, one of the nation's largest. "And we've got to hope that we can educate people to put aside their racism and to put their own interests No. 1." He spoke in an Associated Press interview.

Obama also is battling attacks by McCain, who questions the relative newcomer's national security credentials and is critical of his opposition to offshore oil drilling at a time of record-high gasoline prices.

Obama's campaign has become more aggressive, however, and on Monday unleashed a mocking ad that links McCain with Bush and failed economic policies. The musical commercial underscored a desire by party leaders to use the convention to skewer McCain even as it seeks unity in the Democratic family.

Obama also announced this weekend his choice of Joe Biden, a veteran senator and aggressive campaigner ready to take on McCain despite their decades-long friendship.

But the choice of Biden may have exacerbated tensions with Clinton supporters, many of whom had hoped she would become Obama's running mate.

In remarks to the New York delegation to the Democratic convention here, Clinton declared too much was at stake for the party to remain divided. She cited the next president's hand in naming Supreme Court justices, the need to fix American education, the U.S. energy crisis and foreign policy challenges.

"None of that will happen if John McCain is in the White House. I just want to make it absolutely clear we cannot afford four more years of George W. Bush's failed policies in America, and that's what we would get with John McCain," she said.

Obama will accept his nomination Thursday night in a speech to 75,000 in an outdoor sports stadium. He said Monday he would use the speech to help voters understand what he planned to do to improve the economy. "I'm not aiming for a lot of high rhetoric," he said.

The Republicans hold their convention next week in St. Paul, Minnesota. McCain has begun a busy week of low-key events that is expected to conclude Friday with him announcing his vice presidential pick. The Arizona senator has tempered his rhetoric somewhat, and on Monday, he called Obama his "very honorable opponent."