Some 6,000 people signed up on the New York sUnited States Senator Hillary Clinton speaks to her supporters during a rally in Washington June 7, 2008. Hillary Clinton announced on Saturday to end her running campaign for the presidency and called on her surpporters to vote for her rival, Domocratic presidential hopeful Senator Barak Obama in the presidential election later this year. (Xinhua/Zhang Yan)

U.S. senator Hillary Clinton formally conceded the epic Democratic nomination contest on Saturday to senator Barack Obama, who clinched the nomination earlier this week.

Speaking to a large crowd of supporters at a rally in Washington DC, Clinton said she endorsed Obama, and "throw my full support behind him."

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

To those who voted for her, Clinton said "I will continue to stand strong with you every time, every place and every way that I can."

Speaking of the historic nature of a race between an African-American man and a woman for their party's presidential nomination, Clinton just said that "together, Obama and I achieved milestones essential to our progress as a nation."

Her supporters can be proud, she said, that from now on "it will be unremarkable" to have a woman seeking the presidency.

Some 6,000 people signed up on the New York senator's web site to attend the speech at the National Buildings Museum.

Obama is spending Saturday in his home in Chicago, Illinois.

A CNN poll released shows that the party is divided after a primary season that stretched over nearly 18 months and 57 contests.

Sixty percent of Clinton supporters said they would vote for Obama, but 17 percent said they would vote for Sen. John McCain, the presumptive Republican nominee and Obama's rival in the general election.

Nearly one-quarter, 22 percent, said they would not vote at all if Clinton were not the Democrats' nominee.

Clinton has vowed to do whatever she could "to ensure that Democrats take the White House back and defeat John McCain," and her efforts to reach out to woman and blue-collar voters - groups with which she handily beat Obama -- may be crucial if the Democrats are to take back the White House.

Donna Brazile, a member of the Democratic National Committee and CNN contributor, said it was important after the hard-fought primary season that Obama and Clinton work to promote reconciliation. "There's a lot of healing to be done," she said.

Even some of her own supporters suggested that Clinton may have hurt the reconciliation process when she did not immediately concede the race to Obama after he won the 2,118 delegates needed to capture the party's nomination Tuesday night.