Sen. Hillary Clinton has officially ended her historic quest to be the United States' first female president and has asked her followers to support fellow Democrat Barack Obama.

In a speech at the National Building Museum in Washington on Saturday, Clinton called for unity for the fractured Democratic Party and fully and unequivocally endorsed her rival -- Sen. Barack Obama of Illinois.

The rookie senator is the first black candidate to capture a major U.S. party's presidential nomination. He is going up against Sen. John McCain of Arizona, the presumptive Republican nominee.

"The way to continue our fight now, to accomplish the goals for which we stand is to take our energy, our passions, our strengths and do all we can to help elect Barack Obama the next president of the United States," she said.

"Today as I suspend my campaign, I congratulate him on the victory he has won and the extraordinary campaign he has won. I endorse him and throw my full support behind him and I ask of you to join me in working as hard for Barack Obama as you have for me."

Clinton said she was standing with Obama to say, "Yes, we can," using Obama's signature line.

She began her speech by thanking her supporters: "This isn't exactly the party I planned, but I like the company."

Clinton spoke at length about her quest to be the first female president, and said her campaign proved that a woman could be commander-in-chief.

She said that the highest glass ceiling now has 18 million cracks in it, referring to the amount of votes she received during the grueling primary process that began in early January in Iowa and New Hampshire.

"If we can launch 50 women into space, we can launch a woman into the White House," Clinton said, referring to the fact that Karen Nyberg became the 50th woman astronaut in space last week.

And she told people to never quit and never give up.

Clinton technically only suspended her campaign, a legality that allows her to continue to raise money. Her campaign is about $30 million in debt.

Clinton's supporters starting lining up at dawn to attend the farewell address. A number of Obama supporters attended as well, saying they did so for party unity.

Obama did not attend the speech, and is at home in Chicago this weekend.

It has been 16 months since Obama and Clinton announced their respective bids to become their party's presidential nominee. He secured the 2,118 delegates need to win after the final primaries in South Dakota and Montana on Tuesday.

Many had expected Clinton to suspend her campaign that night, but she surprised analysts with a defiant speech. Many Democrats worried that she'd take her bid all the way to the party's August convention in Denver.

On Thursday, Obama and Clinton met in a secret, hour-long meeting. It has been reported that when the meeting was over, the pair were laughing together.

There has been rampant speculation about Clinton's future. This week she said she was "open" to the vice-presidency, although it is hardly a certainty.

Obama launched a VP search committee on Wednesday.