Democratic presidential candidate Senator Barack Obama and his wife, Michelle, cast their votes in Chicago, Illinois yesterday. Obama won the election and assumes the presidency on January 20. - AP

WASHINGTON (AP):

Amid euphoric celebrations after claiming a historic electoral victory, United States President-elect Barack Obama this morning cautioned Americans that "the road ahead will be long".

"Our climb will be steep. We may not get there in one year or even one term but, America, I have never been more hopeful than I am tonight," he said to tens of thousands who gathered at a victory rally in Chicago's Grant Park.

"If there is anyone out there who still doubts that America is a place where all things are possible; who still wonders if the dream of our founders is alive in our time; who still questions the power of our democracy, tonight is your answer," the new president said.

He spoke warmly of John McCain, the 72-year-old Arizona senator who was his rival in the longest and most costly presidential campaign in American history.

After McCain called Obama to concede victory, he spoke graciously of him at an outdoor rally in Arizona, commending the president-elect on his victory and emphasising that he understood its special importance to African-Americans.

"The American people have spoken, and spoken clearly," McCain told disappointed supporters in Arizona, many who booed and growled as he called for the nation to unify behind the victor and his running mate, Joe Biden.

Milestone

Obama stepped through a door opened 145 years ago when Abraham Lincoln, a fellow Illinois politician, issued the Emancipation Proclamation that freed African-Americans from enslavement in the rebellious South in the midst of a wrenching civil war.

Cheering, screaming and waving flags, an estimated 50,000-plus Obama supporters welcomed his election in a delirious victory celebration in the senator's hometown.

Watching the results on a jumbo TV screen, the crowd erupted in cheers each time Obama put yet another state in his victory column.

The assembled backers were treated to one of Obama's most uplifting speeches.

"To those who would tear this world down we will defeat you. To those who seek peace and security, we support you," he said. "And to all those who have wondered if America's beacon still burns as bright tonight, we proved once more that the true strength of our nation comes not from our the might of our arms or the scale of our wealth, but from the enduring power of our ideals: democracy, liberty, opportunity and unyielding hope."