Clinton, who was once once so certain that she would win the Democratic nomination this year, also took steps on Tuesday to keep the door open to a future bid for the presidency. She rallied supporters in her speech, and, at an earlier event with 3,000 women, described her passion about her own campaign. And her aides limited input on the speech from Obama advisers, while seeking advice from her former strategist, Mark Penn, a loathed figure in the Obama camp.

But the main task for Mrs. Clinton at the convention — reaffirming her support for Mr. Obama in soaring and unconditional language — dominated her 23-minute speech, and she betrayed none of the anger and disappointment that she still feels and that, friends say, has especially haunted her husband.

Declaring herself to be “a proud supporter of Barack Obama,” Clinton urged Democrats to unite behind Obama or risk continuing Bush administration policies under the presumptive Republican nominee, Senator John McCain.

“Whether you voted for me, or voted for Barack, the time is now to unite as a single party with a single purpose,” Clinton said. “And you haven’t worked so hard over the last 18 months, or endured the last eight years, to suffer through more failed leadership. “No way, no how, no McCain,” she added.

Indeed, Clinton provided some of the night’s sharpest lines of attack on McCain. “It makes sense that George Bush and John McCain will be together next week in the Twin Cities,” she said, referring to the site of the Republican National Convention, “because these days they’re awfully hard to tell apart.”

Introduced by her daughter, Chelsea, who called her “my hero,” Clinton was met with a long, loud standing ovation. She sprinkled her opening remarks with personal touches, delighting the crowd by thanking “my supporters, my champions — my sisterhood of the traveling pantsuits,” a reference to her signature sartorial style. “You never gave in, you never gave up, and together we made history,” she said.

Former President Bill Clinton became teary at several points during his wife’s speech, and even Clinton — who has been so steady this week — seemed to grow misty a couple of times as she profusely thanked her supporters and recalled some of the Americans she met along the trail.

Obama listened to the speech on TV at a convention-watching party elsewhere. Michelle Obama sat with her brother, Craig; Senator Joseph R. Biden Jr., Obama’s running mate; and former President Jimmy Carter. Bill Clinton sat in his own row.

Clinton advisers said she wanted to cement her image as a heroine of women and working-class and middle-class Americans, three groups that Obama is struggling to win over. They added she may start her own effort on behalf of female women’s concerns, tapping millions of supporters and donors and perhaps using her political action committee, HillPac, as a vehicle.

At the same time, advisers said, she wanted to ensure that her star turn at the convention could never be portrayed as being insufficiently enthusiastic.

She is almost certain to run for president in 2012 if Obama fails this time, several Clinton advisers said on Tuesday, and any such impression could possibly founder if the Clintons’ negative feelings show through this year.