DENVER — Democrats used the opening night of their convention here to paint a gauzy, middle-American image of the party’s presumptive nominee for president, Senator Obama, and his wife, Michelle.

“I come here as a wife who loves my husband and believes he will be an extraordinary president,” Mrs. Obama told the assembled delegates. “I come here as a mom whose girls are the heart of my heart and the center of my world — they’re the first thing I think about when I wake up in the morning, and the last thing I think about before I go to bed at night. Their future — and all our children’s future — is my stake in this election.”

Mrs. Obama also stressed her husband’s devotion to family. “The Barack Obama I know today is the same man I fell in love with 19 years ago,” she said. “He’s the same man who drove me and our new baby daughter home from the hospital 10 years ago this summer, inching along at a snail’s pace, peering at us anxiously in the rearview mirror, feeling the whole weight of her future in his hands, determined to give her everything he’d struggled so hard for himself, determined to give her something he never had: the affirming embrace of a father’s love.”

While wives are often trotted out to soften the images of their politician husbands, Mrs. Obama’s speech seemed intended as much to counter perceptions, stoked by some conservatives, that she is strident and aggrieved. That sense was fueled by her comment in February that “for the first time in my adult life I am proud of my country.”

Last night, Mrs. Obama called America “this great country — where a girl from the South Side of Chicago can go to college and law school, and the son of a single mother from Hawaii can go all the way to the White House.”

With the Obamas under political attack as elitists, Mrs. Obama never mentioned that she attended Princeton and Harvard, while her husband went to Columbia and Harvard. The wife of the presumptive Democratic nominee also briefly saluted Senator Clinton for putting “18 million cracks in that glass ceiling.”

After Mrs. Obama spoke, her children walked out on stage and Mr. Obama appeared on a huge video screen to chat with them. “How about Michelle Obama?” he asked the crowd. “Michelle, you were unbelievable,” he said.

The emotional high point of the night came when Senator Kennedy, who was diagnosed with an aggressive brain tumor in May, strode onto the stage, accompanied by his wife, Victoria.

“It is so wonderful to be here. And nothing, nothing, is going to keep me away from this special gathering tonight,” Mr. Kennedy said to a chorus of knowing cheers. “I have come here tonight to stand with you, to change America, to restore its future, to rise to its best ideals, and to elect Barack Obama president of the United States.”

Mr. Kennedy also spoke about the appeal of Mr. Obama’s racial background more frankly than the candidate and his most prominent supporters usually do in public. “Barack Obama will close the book on the old politics of race and gender, and group against group, and straight against gay,” the senator of Massachusetts said.

The so-called liberal lion of the Senate also alluded to Mr. Obama’s opposition to the Iraq war. “Barack Obama will be a commander in chief who understands that young Americans in uniform must never be committed to a mistake, but always to a mission worthy of their bravery,” Mr. Kennedy said.

While some close to Mr. Kennedy raised questions about whether his health would even permit him to make the trip to Denver, let alone address the crowd, the veteran senator spoke forcefully. During his eight-minute speech, he stuck to the text on the teleprompter and never let loose the thunderous, ruddy-faced verbal salvos he often unleashed before his cancer diagnosis, though at times he came close. At several points, cries of “Teddy! Teddy!” forced him to interrupt his remarks.

Mr. Kennedy never explicitly mentioned his battle with cancer, but when he vowed to stay on in the Senate, the crowd let out an especially loud roar. “I pledge to you that I will be there next January on the floor of the United States Senate,” he declared.

Mr. Kennedy was preceded by his niece, Caroline Kennedy Schlossberg, who is also the daughter of President Kennedy.

“I’ve never had someone inspire me the way people tell me my father inspired them — but I do now: Barack Obama,” she declared. “And I know someone else who’s been inspired all over again by Senator Obama: In our family, he’s known as Uncle Teddy. More than any senator of his generation, Teddy has made life better for people in this country and around the world.”

The focus on Mr. Kennedy was intended, in large part, to win over the older Democratic voters, who have been most resistant to Mr. Obama’s candidacy. However, Ms. Schlossberg also felt the need essentially to introduce her uncle to Mr. Obama’s younger voters, many of whom were not yet born when Mr. Kennedy was in the national spotlight during his unsuccessful bid for the Democratic presidential nomination in 1980.

Mr. Kennedy walked haltingly and with help from Ms. Schlossberg as he left the stage to the song “Still the One.”

One of several videos played in the hall last night, a tribute to President Carter, focused on the devastation Hurricane Katrina visited on New Orleans in 2005 and on the lackluster response by the federal government. The clip highlighted Mr. Carter’s work to rebuild the devastated area, but made no reference to Mr. Carter’s more polarizing statements and writings on foreign policy or, specifically, Israel’s treatment of Palestinian Arabs.

While organizers worked to limit references to the division between some ardent supporters of Mrs. Clinton and those of Mr. Obama, at least one seeped through last night. In one of the first speeches yesterday, a longtime Clinton supporter who served as co-chairwoman of the Platform Committee, Judith McHale, spoke of “strongly denouncing sexism which sadly continues to be prevalent throughout our society.” The statement, which echoed the concerns of Democrats who believe sexism in the press and elsewhere unfairly hampered Mrs. Clinton’s campaign, drew scattered cheers in the hall.

A short time later, a key backer of Mrs. Clinton, Rep. Joe Baca of California, badly mangled Mr. Obama’s name while praising him from the podium. “As a Latino, I am here to say our community is proud to support Barack Barama as the next president of the United States of America,” Mr. Baca declared. Television shots showed delegates in the hall reacting with quizzical expressions and confusion. Mr. Baca did get out the name correctly at other points in his brief speech.