Miliband

David Miliband, pictured with his wife, Louise, outside their London home, said he would not stand for the shadow cabinet. Photograph: Andy Rain/EPA

David Miliband today confirmed he was quitting frontline politics, but promised to serve the Labour party and his younger brother's leadership to his utmost from the backbenches.

Ed Miliband, the Labour leader, responded by saying his door was always open for his brother to return to the front bench in the future.

The defeated Labour leadership candidate insisted that stepping back from the political limelight was the "cleanest and clearest thing to do although not the most obvious or easy thing to do" in order to allow Ed Miliband to set the future direction for the party free of permanent scrutiny of any potential differences between the two men.

Ed Miliband, looking notably relaxed as he spoke outside Labour's Manchester conference, said that while it would have been "fantastic" to have had his older brother as part of his team, David's decision was "thoughtful and gracious".

"My door is always open for him to serve in the future," Ed Miliband said.

Other colleagues paid tribute to David Miliband, who has served on the frontbenches since 2002 – a year after he was elected to parliament – and was seen as a frontrunner in the Labour leadership until the final few days of the race, when the odds switched in favour of his younger brother.