"This isn't exactly the party I planned, but I sure like the company," she told thousands of supporters.
Clinton ended her more than 16-month campaign in a speech before a raucous crowd in Washington, DC during which she fully endorsed the candidacy of Ill. Sen. Barack Obama.
"I understand that we all know that this has been a tough fight, but the Democratic party is a family and now it's time to restore the ties that bind us together," she told cheering supporters at the National Building Museum.
"Today as I suspend my campaign, I congratulate him on the victory he has won, the extraordinary race he has run and I throw my full support behind him -- and I ask all of you to join me in working as hard for Barack Obama as you have for me," she said to loud applause and some boos.
The endorsement came less than two days after Obama and Clinton met face-to-face. The two held what were described as cordial private talks in the home of Sen. Dianne Feinstein Thursday night.
The possibility of an Obama-Clinton ticket remained unclear, but officials have said it is a prospect Clinton has said she would not oppose.
"[Clinton] has said if Senator Obama should want her to be vice-president and thinks it would be best for the ticket, she will serve, she will accept that. But on the other hand, if he chooses someone else, she will work just as hard for the party in November," Schumer, Clinton's New York colleague in the Senate, told ABC's Good Morning America.
Obama has formed a committee including Caroline Kennedy, the daughter of President Kennedy, to oversee the vice presidential selection.
On Monday, Obama travels to North Carolina to kick off two weeks of town hall meetings, rallies and speeches, looking to build on the huge national organization built during the bruising Democratic primary. But he had no plans on Saturday and stayed away from the Clinton rally, giving his one-time opponent and now endorser her moment on the national political stage.
During her campaign, the former first lady garnered the support of more than 17 million Democratic voters, secured the backing of some 1900 delegates, and won 23 contests around the country.
Saturday, she thanked those supporters, expressing appreciation for the strong support she received among women voters and lower and middle class workers.
"Eighteen million of you from all walks of life -- women and men; young and old: Latino and Asian, Caucasian and African American; rich, poor and middle class; gay and straight -- you have stood with me and I will stand with you," Clinton said to repeated cheers of "Hillary! Hillary!"
She also addressed the historic nature of her campaign, changing her campaign trail talk of being a candidate who happens to be a woman to address the impact of what her campaign had achieved.
"I am a woman, and like millions of women, I know there are still barriers and biases out there, often unconscious, and I want to build an America that respects and embraces the potential of every last one of us," Clinton told the crowd to wild applause.
"Let us resolve and work toward achieving very simple propositions, there are no acceptable limits and there are no acceptable prejudices in a 21st century America," she added.
Some within the party still expressed anger over the way the media and some analysts discussed the Clinton candidacy, including heavy coverage of an episode where she appeared to tear-up in New Hampshire and the conflicting role of her husband, former President Bill Clinton.
"The wounds of sexism need to be the subject of a national discussion," the chairman, Howard Dean, said in an interview with The New York Times. "Many of the most prominent people on TV behaved like middle schoolers" toward Clinton.
But during her speech she also returned to the core issues both Democrats had focused on in their campaigns. Her litany of issues, ranging from health care to the economy to the war in Iraq all ended with the same rousing endorsement of her long-time opponent, with the senator saying, " "...and that is why we must help elect Barack Obama our president."
The full-throated endorsement came only days after many Democrats expressed frustration and anger when Clinton refused to acknowledge Obama's victory on Tuesday when he officially past the number of delegates needed to win the Democratic nomination.
"You know, I understand that that a lot of people are asking, 'What does Hillary want? What does she want?'" Clinton told cheering supporters that night in New York. "Well, I want what I have always fought for in this whole campaign... I want the nearly 18 million Americans who voted for me to be respected, to be heard and no longer to be invisible."
She said she would take her time in deciding what to do next.
"This has been a long campaign and I will be making no decisions tonight, but this has always been your campaign," Clinton said, urging people who had voted for her to visit her Web site and offer their thoughts about what she should do.
The Clinton campaign received some 350,000 email responses, many with "an overwhelming chorus of 'We want you to continue to be our leader,'" said Ann Lewis, a Clinton adviser.
As she ended her campaign for the Democratic nomination, instead of claiming the role of leader of a wing of the Democratic Party, Clinton instead sounded a Moses-like note for women in America.
"You can be so proud that from now on it will be unremarkable for a woman to win primary-state victories," Clinton said. "The path will be a little easier next time... that has always been the history of progress."
"Although we weren't able to shatter that highest, hardest glass ceiling, thanks to you it's got about 18 million cracks in it and the light is shining through like never before," she said.