Mitt Romney urged America's leaders to "reach across the aisle" in a brief but poignant concession speech at the Boston Convention and Exhibition Center shortly before 1 a.m. on Wednesday.
Romney said he had called President Barack Obama to concede, and wished him and his family the best.
"I pray that the President will be successful in guiding our nation," he said.
Romney thanked his staff and supporters. He also praised his running mate, Paul Ryan.
"Besides my wife Ann, Paul is the best choice I ever made," he said.
"I believe that Paul and I have left everything on the field, we have given our all to this campaign," he said.
But the crux of Romney's speech was a plea for America's leaders to move on from the divisive politics of recent years.
"We look to Democrats and Republicans in government at all levels to put the people before the politics," he said.
Romney said he believes in America.
"The nation, as you know, is at a critical point," he said. "At a time like this, we can't risk partisan bickering. Our leaders have to reach acorss the aisle to do the people's work."