(changes dateline, re-ledes with Romney concession)
Mitt Romney conceded the U.S. presidential election to incumbent Barack Obama in a brief address to supporters here at 1:00 a.m. Wednesday.
Television networks had called Tuesday's election for the Democrat shortly after 11:00 p.m., but the Republican hopeful's campaign said he was not ready to concede.
Romney made his concession speech at a Boston hotel after telephoning the president to congratulate him on his victory.
"We have given our all to this campaign," the former governor said. "I so wish that I had been able to fulfill your hopes to lead your country in another direction."
The networks made their projections based on Obama's leads in the swing states of Ohio and Iowa.
With 55 percent of the ballots counted in Iowa, Obama led his Republican challenger by 55 percent to 44 percent.
In Ohio, the Democrat was ahead by 50 percent to 49 percent with 73 percent of votes tabulated. In the past 50 years, no one has secured the White House without winning the Buckeye State's 18 electoral votes.
Pending final results in important states such as Florida and Virginia, Obama was expected to finish with 303 electoral votes, compared with 206 for Romney.
A candidate needs 270 electoral votes to win.
"This happened because of you. Thank you," Obama told his supporters on Twitter after the networks projected him as the winner.
"Four more years," he added.
The nation's first black president will again face a divided Congress when he begins his second term in January, as media projections showed the GOP retaining control of the House of Representatives and Democrats maintaining a majority in the Senate. EFE