In Manchester, David Miliband called for party members to support his brother Ed Miliband as leader, and asked them to quit internal bickering and look to the future, London's Daily Telegraph newspaper reported.
David Miliband, Britain's shadow foreign minister, said his younger brother's selection was a surprise, and that he had prepared a victory speech he planned to give following the election.
The younger Ed Miliband was picked to lead the left-center Labor Party by just 1.3 percent of the votes in Saturday's election, and political observers speculated Ed Miliband might offer his brother David the shadow chancellor role as a consolation prize.
"I've been incredibly honored and humbled by the support that you have given me," David Miliband said. "But we have a great new leader and we all have to get behind him."
Miliband succeeds Labor Party leader Gordon Brown. The elder Miliband said he wants to take some time to consider his political future, the report said.