WASHINGTON (CNN) -- Sen. Edward Kennedy backed Sen. Barack Obama for president Monday, saying, "It is time again for a new generation of leadership."
Sens. Edward Kennedy and Barack Obama are all smiles after Kennedy endorsed Obama.
"It is time now for Barack Obama," the Massachusetts senator and brother of the late President Kennedy added.
He stood with Obama, his son, Rep. Patrick Kennedy, and his niece, Caroline Kennedy, before a screaming capacity crowd of students at American University in Washington.
"Like you, we want a president who appeals to the hopes of those who still believe in the American dream," he said.
"I've found that candidate. And it looks to me like you have too," he said. Watch Kennedy compare Obama to JFK »
After Kennedy spoke, Obama told the boisterous crowd: "I know what your support means. I know the cherished place the Kennedy family holds in the hearts of the American people."
The Illinois Democrat said he would work to carry on the vision the senator's brother laid out when he was president nearly five decades ago.
"The dream has never died ... it lives on in those Americans, young and old, rich and poor, black and white, Latino and Asian and Native American, gay and straight, who are tired of a politics that divides us and want to recapture the sense of common purpose that we had when John Kennedy was president of the United States of America," Obama said.
"That is the dream we hold in our hearts," Obama said. "That is the kind of leadership we long for in this country. And that is the kind of leadership I intend to offer as president of the United States of America."
Kennedy said he has always planned to "support the candidate who inspires me, who inspires all of us, who can lift our vision and summon our hopes and renew our belief that our country's best days are still to come." Watch Obama explain why Kennedy decided to endorse him »
Picking up on Obama's central campaign theme, he said, "I feel change in the air. What about you?"
Kennedy praised Sen. Hillary Clinton and former Sen. John Edwards, saying Edwards "has been a powerful advocate for economic and social justice. And Hillary Clinton has been in the forefront on issues ranging from health care to the rights of women around the world.
"Whoever is our nominee will have my enthusiastic support," he said.
But he also took a line from Clinton's campaign, saying Obama "is ready to be president on Day 1."
In what may have been a veiled swipe at Clinton, Kennedy said of Obama, "From the beginning, he opposed the war in Iraq. And let no one deny that truth."
Clinton has pointed to various statements Obama has made about Iraq, suggesting he has not been consistent -- an accusation he has denied.
Kennedy -- a fixture of the Democratic Party popular with many liberals -- was introduced by Caroline Kennedy, who spoke of her father, the slain president. She said Obama offers the "sense of hope and inspiration" that Americans today need. In fact, she said, her children "were the first people who made me realize that Barack Obama is the president we need."
The New York Times reported Monday that Sen. Kennedy endorsed Obama despite pleas from the Clinton camp to remain neutral in the Democratic race.
The Massachusetts senator decided to endorse Obama after becoming concerned about the often-bitter campaigning involving former President Clinton before Saturday's South Carolina primary, which Obama won, the newspaper reported.
The Times said Kennedy was angry the former president had introduced what he felt were racial themes into the campaign and that Bill Clinton had made misleading statements about Obama, matters Kennedy and Clinton discussed during two heated telephone conversations earlier this month.
Caroline Kennedy endorsed Obama in a weekend New York Times editorial.
Members of the Kennedy clan are split in the race. Former Maryland Lt. Gov. Kathleen Kennedy Townsend issued a statement Sunday stating her support for Clinton.
"I respect Caroline and Teddy's decision, but I have made a different choice," she said. "While I admire Sen. Obama greatly, I have known Hillary Clinton for over 25 years and have seen firsthand how she gets results. As a woman, leader and person of deep convictions, I believe Hillary Clinton would make the best possible choice for president."
She added that her brother Bobby and sister Kerry are also backing Clinton.
Kennedy Townsend is the oldest child of Robert F. Kennedy.
Sen. Kennedy's decision to endorse Obama could help Obama's campaign as he seeks momentum toward Super Tuesday on February 5, when 22 states and American Samoa will weigh in on the Democratic race. In polls, Obama has trailed Clinton nationally.
Obama, coming off the South Carolina victory, has been seeking to expand his support nationwide. He won that state with the help of a large majority of African-American voters, while most white voters supported Clinton or Edwards.
Sen. Kennedy spoke enthusiastically, interrupted by frequent applause from the young crowd.
"When John Kennedy thought of going to the moon, he didn't say no, it was too far, maybe we couldn't get there and shouldn't even try," he said.
"I am convinced we can reach our goals only if we are not petty when our cause is so great -- only if we find a way past the stale ideas and stalemate of our times -- only if we replace the politics of fear with the politics of hope -- and only if we have the courage to choose change.
"Barack Obama is the one person running for president who can bring us that change. Barack Obama is the one person running for president who can be that change." E-mail to a friend
CNN's Josh Levs contributed to this report.