The battle for the White House between the top Republican and Democratic contenders was set to begin in earnest Sunday after Democrat Hillary Clinton formally bowed out of the race and threw her support behind Barack Obama.
Clinton's quest to be the first woman commander in chief ended with her imploring her backers to vote for Obama, saying he was a man of "grace and grit" who was, like her, tilting at history after living the American dream.
"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," Clinton said, basking in the devotion of around 2,000 supporters at a raucous rally.
"Today, as I suspend my campaign, I congratulate him on the victory he has won and the extraordinary race he has run," said Clinton, who angered some Democrats with her defiant tone after Obama clinched the nomination last week.
Obama, vying to become the first African-American president in US history, welcomed her endorsement and paid tribute to her "valiant and historic" campaign.
"No one knows better than Senator Clinton how desperately America and the American people need change, and I know she will continue to be in the forefront of that battle this fall and for years to come," Obama said in a statement.
Obama now faces a tough fight against Republican presumptive nominee John McCain after the turbulent Democratic contest which has torn at party unity. But The Los Angeles Times noted in an editorial Sunday the two candidates actually have more in common than they are willing to let on.
"Surprisingly, given McCain's reputation as a hawk and Obama's as a peacenik, they don't differ much in their ideas about how best to protect the country," the paper said.
"Both want to increase the size of the military and provide more training and equipment. Both oppose the use of torture as an interrogation technique, and both would like to close the Guantanamo Bay detention center." Clinton gave a ringing endorsement of Obama in a gracious speech in Washington's ornate National Building Museum, which positioned her as a historic figure who shattered gender barriers.
She borrowed Obama's "yes we can!" mantra, and repeatedly told her army of faithful, 18 million supporters that they must put her former rival in the White House. "The Democratic Party is a family, and now it is time to restore the ties that bind us together and to come together around the ideals we share, the values we cherish and the country we love," she said.
In a speech which marked the end of an era, with her family shuffling off center stage for the first time in 16 years, Clinton had former president Bill Clinton and daughter Chelsea at her side in the museum's ancient Rome-style Great Hall. Terry O'Neill, a Clinton supporter from Bethesda, in suburban Maryland, said it was now up to Obama to win over the former first lady's millions of supporters.
"She earned my support by her leadership on issues important to me," she said. "I know he is open-minded, he is pro-choice (backs abortion rights) he is a Democrat. Now it is up to him to earn my support."
Clinton's constituency of working-class whites, women and Hispanics could play a key role in sending Obama to the White House, expanding his powerbase of African-Americans, young voters and more affluent Democrats.
After an often bitter campaign, the New York senator began to build bridges with Obama in a secret meeting with him on Thursday night, which fanned more speculation about her vice presidential prospects. Clinton's speech was the final act in a near 17-month odyssey which has encompassed two winters, the snows of Iowa and the dry heat of Nevada, gritty towns of Pennsylvania and swank Hollywood fundraisers. The former first lady, 60 led national polls by huge margins last year, but her campaign was stunned by her loss in the leadoff Iowa caucuses on January 3.
She pulled off a dramatic comeback in New Hampshire days later, but her front-runner strategy-she ran virtually as an incumbent-was buckled by Obama's soaring message of hope and change, and superb campaign organisation. After she failed to knock Obama, 46, out in the Super Tuesday nation-wide primary contests in February, Clinton was always behind, despite clinging on with big victories in states like Ohio and Pennsylvania.