Washington - Republican John McCain quickly conceded defeat in Tuesday's election, congratulating Democrat Barack Obama for his historic victory and urging Americans to help the new president meet the country's challenges.

Speaking from his campaign headquarters in Phoenix, Arizona, McCain told his supporters to cast aside differences with Obama and the Democrats. McCain, 72, said he telephoned Obama, 47, a few minutes earlier to congratulate Obama and his family.

"I wish Godspeed to the man who was my former opponent and will be my next president," McCain said in an address delivered within a few minutes of the closing of polls on the West Coast, when the outcome was obvious.

Obama had quickly captured enough states to easily top the threshold of 270 votes in the Electoral College, making him the first African-American president.

"We have come to the end of a long journey," McCain told supporters. "The American people have spoken, and they have spoken clearly."

Obama prevailed in the election after capturing Ohio, Florida, Virginia, New Mexico and Iowa, all states won by President George W Bush in 2004. Bush's unpopularity as he prepares to leave office after eight years proved an insurmountable obstacle for fellow Republican McCain.

The Arizona senator thanked his supporters and campaign staff, and praised his vice presidential running mate, Alaska Governor Sarah Palin.

"It is natural, though, to feel some disappointment, but tomorrow we must move beyond it," McCain said. "We fought as hard as we could, and though we fell short, the failure is mine - not yours." (dpa)