Britain's former foreign minister David Miliband has criticised his brother Ed's leadership of the Labour Party, saying voters "did not want what was being offered".
He told said the leadership had allowed itself to be portrayed as "moving backwards".
But Mr Miliband, who was beaten to the job of leader by his younger sibling in 2010, also said the two of them would "remain brothers for life".
He ruled himself out of becoming the party's next leader, which would not be possible as he is not an MP.
Mr Miliband quit parliament in 2013 to work for the International Rescue Committee charity in New York.
Ed Miliband resigned as Labour leader in the aftermath of the general election, which left his party on 232 seats, with the Conservatives securing an overall majority.
His approach was also criticised at the weekend by former Business minister Lord Mandelson, while some of the MPs tipped to replace him have spoken of the need to appeal to "aspirational" voters.
Speaking to the BBC David Miliband said there was "absolutely no point in blaming the electorate" for the election result.
"They didn't want what was being offered," he said.
He said his brother and, before him, former Labour prime minister Gordon Brown had "allowed themselves to be portrayed as moving backwards from the principles of aspiration and inclusion that are the absolute heart of any successful progressive political project".
He added: "Either we build on what Labour achieved after 1997 and we have a chance to succeed, or we abandon it and we fail."
But he said he remained in touch with his younger brother, adding that "many of the attacks on Ed were unpleasant and unfair and I think he dealt with them with enormous dignity and with courage. I've always said you remain brothers for life and that's something that has to be kept".
Asked whether Labour would be better off if he had been chosen as leader, Mr Miliband said there was "no point in trying to press the rewind button in life".