DENVER (AP) -- Ailing and aging, Sen. Edward M. Kennedy summoned fellow Democrats to rally behind Barack Obama's pioneering quest for the White House Monday night in an emotional opening to a party convention struggling for unity essential in the fall campaign.

The 76-year-old party icon looked out at a sea of white and blue signs bearing his name as he urged delegates in the hall and millions watching at home to "rise to our best ideals" in the election.

"The work begins anew, the hope rises again and the dream lives on," Kennedy said in a strong voice, reprising the final line of a speech at the 1980 convention that brought a different convention to its feet. The senator has been undergoing treatment for a malignant brain tumor.

Later, Obama's convention planners used a prime time address by his wife, Michelle, to begin the work of casting him as a leader with classic American values."

Among them, she said in prepared remarks; "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."

Her turn in the spotlight aside, one labor leader spoke plainly about the challenge ahead.

"There are people who are not going to vote for him because he's black," said James Hoffa, president of the Teamsters. "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.

In one of their first orders of business, delegates ratified a party platform tailored to Obama's specifications. It backs "complete redeployment within 16 months from Iraq," as well as health care for all, a new economic stimulus package and higher taxes on families earning over $250,000 a year.

"The Democratic Party strongly and unequivocally supports Roe v. Wade and a woman's right to choose a safe and legal abortion, regardless of ability to pay, and we oppose any and all efforts to weaken or undermine that right," it said.

The convention's opening gavel fell with Obama and Hillary Rodham Clinton still struggling to work out the choreography for the formal roll call of the states that will make him - a 47-year-old senator bidding to become the first black president - the party nominee.

"There is no doubt in anyone's mind that this is Barack Obama's convention," the former first lady told reporters. And yet, she said, some of her delegates "feel an obligation to the people who sent them here" and would vote for her.

The young Illinois senator also fought on a second front, moving to quash a television commercial linking him to a 1960s-era radical before it could damage his candidacy as the infamous Swift Boat ads sank John Kerry four years ago.

As the delegates took their seats in the Pepsi Center, Obama campaigned in Iowa, the first in a string of swing states he is visiting en route to Colorado. He arranged to watch his wife's speech on television later from Kansas City, then speak briefly to the convention via a huge TV screen.

Public opinion polls made the race with Republican John McCain a close one, unexpectedly so given a widespread desire for change in an era of economic uncertainty, continuing conflict in Iraq and poor approval ratings for GOP President Bush.

Obama delivers his acceptance speech on Thursday at a football stadium, before a crowd likely to total 75,000 or more. Then he and Sen. Joseph Biden of Delaware, his vice presidential running mate, depart for the fall campaign.

If the opening night's convention program had a feel-good quality, not so the intensifying campaign outside the hall.

Obama shipped a new commercial that used humor to depict McCain as an extension of the Bush administration, the latest in a series of negative advertisements by both sides.

"Really can't explain the price of gas, or what has happened to the middle class," the announcer sings to the tune of Sam Cooke's "Wonderful World." With McCain and Bush appearing together on the screen, the announcer says, "Do we really want four more years of the same old tune?"

While the White House is the biggest prize of the election year, prominent Democrats expressed optimism in Associated Press interviews about major gains in the fall in races for the House and Senate.

Rep. Chris Van Hollen, D-Md., said 70 or more House seats are competitive, the majority of them currently in Republican hands.

Sen. Chuck Schumer, D-N.Y., said fashioning a 60-seat, filibuster-proof Senate majority was a stretch. But he added that Democrats lead for five seats currently in Republican hands, and several others are competitive.

Howard Dean, the party chairman, rapped the opening gavel precisely on schedule at 3 p.m. Mountain Time - before only a smattering of delegates.

"We are ready to compete in all 50 states in November," he said, even though Obama has already written off large portions of the South and Mountain West.

Schumer and Van Hollen said only a small fraction of Clinton's delegates remained unreconciled to Obama's triumph in the bruising primaries of the winter and spring.

Perhaps so, but they were vocal about it, and officials said one of the issues under discussion was whether to permit a noisy floor demonstration by Clinton's supporters when the former first lady's name is placed in nomination on Wednesday night.

Kathleen Kennedy Townsend, the eldest child of the late Robert F. Kennedy and a former lieutenant governor of Maryland, said the animosity that some Clinton delegates feel toward Obama is worsening. "There's a moment that you want to enjoy your bitterness," she said, although she emphasized that she is supporting Obama.

Another Maryland delegate, Mary Boergers said she didn't care what Clinton's wishes were about whom to support on a roll call. "To try to suppress the celebration that we all want to have about her achievements is what would tear this party apart," she said.

Boergers, a lifelong Democrat, added she is unsure whether she will vote for Obama in November.

Obama told reporters that his former rival and her husband, former President Bill Clinton, "couldn't have been more clear" in their support for his candidacy.

But the sniping was impossible to miss.

"I'm getting a lot of calls and e-mails, especially from women, who are quite upset that she was not vetted (for vice president) even though senator Obama said she was on the short list," said Lanny Davis, a longtime Clinton loyalist.

All the talk about disunity was grating on some.

"To stay wallowing in all of this is not productive," said House Speaker Nancy Pelosi of California.

"So we can talk about this forever, or we can talk about how we're going to take our message to the American people, to women all across America, to see the distinctions" between Obama and McCain.

Obama's campaign set that as one of the principal goals of the convention week.

"Obama's major challenge at this convention is to focus on the middle class, to show empathy because he had to climb his way up," to demonstrate he has plans to remedy their concerns and the ability to get things done in Washington, Schumer said.

But first came the tribute to Kennedy, now 76 and battling brain cancer. After flying to Denver, he was expected to be in the hall for the video tribute, although Democrats insisted they did not know if he would speak.

Even so, his presence "gives everyone a big lift," Schumer said of the last surviving brother of the late President John F. Kennedy and a party icon across more than four decades in the Senate.

Kennedy's decision to endorse Obama in the early days of the primary campaign was a turning point, not only because it was a ceremonial passing of the torch but also because of his ability to serve as a political reference of sorts for Hispanics, union workers and others.