LONDON — David Miliband, the former British foreign secretary who lost a party leadership contest to his younger brother, said Wednesday that he was quitting front-line politics, drawing to an end a fraught sibling rivalry that had divided both a family and a political party.
“British politics will be a poorer place without David,’’ Ed Miliband, leader of the Labor Party, said after his brother announced that he would take a job in New York running the International Rescue Committee, a humanitarian and aid organization founded to help Jews fleeing the Nazis.
Once seen as the Labor Party’s leader in waiting, David Miliband, 47, will resign his parliamentary seat, ruling out the possibility of his playing any role in British politics for the foreseeable future.
That ends a fraternal rivalry likened by some commentators to the plot of ‘‘The Tempest,’’ in which Prospero loses a dukedom to his brother, Antonio.
In an interview with the BBC on Wednesday, David Miliband said he feared being a distraction in whatever role he played, either as part of his brother’s team or outside it.
‘‘I want it to be the vision Ed has versus the vision David Cameron has,’’ said David Miliband, referring to the Conservative prime minister, ‘‘not Ed and David Miliband.’’
The decision to quit British politics appears to reflect the realization that Ed Miliband now looks firmly ensconced as Labor leader after a shaky start. Effectively, David Miliband faced the difficult prospect of many years in the shadow of his younger sibling after their leadership fight two years ago.
The brothers are both former ministers in the government led by Gordon Brown and sons of a left-wing Jewish intellectual and historian,Ralph Miliband, who reached Britain in 1940 on the last ship to leave Belgium ahead of advancing Nazi forces.
Though as foreign secretary David Miliband could probably have destabilized Brown’s leadership and taken over before the last election in 2010, he held back, perhaps calculating that it was better to succeed in opposition after an inevitable electoral defeat for Labor. If that was the case, he had not counted on the prospect of being usurped by his younger brother, Ed, 43.
David Miliband was seen as the candidate preferred by supporters of former Prime Minister Tony Blair, and Ed Miliband saw a political opportunity by courting the left of the party.
In the leadership contest, David Miliband won greater support among Labor lawmakers, but Ed Miliband cultivated the trade unions, which retain an important say in the choice of leader, winning by a narrow margin.