Ed and David Miliband make Labour leadership pitch
The two brothers vying for the Labour leadership have been setting out their visions for the party in newspaper interviews.
In the Daily Telegraph, Ed Miliband said he would end a New Labour culture that "stifled debate" in the party.
His older brother David Miliband told the Times how he and his wife decided to adopt children after failing to conceive naturally.
They and other candidates are due to speak at a debate in London later.
Left wing MP Diane Abbott, Ed Balls and former Health Secretary Andy Burnham are also in the contest.
Ed Miliband said he would make a "tough and uncompromising leader of the opposition".
But he criticised some of New Labour's record.'Centralising culture'
Mr Miliband said: "New Labour gave the party a stifling culture when it came to debate, a stifling culture when it came to disagreement and when it came to hearing voices of party members.
"We'd have avoided a lot of the problems we got into if we hadn't had the centralising culture that, ironically, we attacked old Labour for."
The former energy and climate change secretary, who said he backed Harriet Harman's call for half the cabinet to be women, also admitted the last government "wasn't right on civil liberties".
David Miliband, the former foreign secretary, told of the "emotionally exhausting" experience of being unable to conceive a child with his wife.
End Quote David Miliband MP
We lost the twin mantles of New Labour's dominance - fairness and change”
He said: "It was a long process. We didn't just go to the doctor and find out, it took years.
"It was very drawn out and difficult but there was a moment we realised we had reached the end of the line and weren't going to give birth."
Mr Miliband and his wife adopted new-born babies from the US.
He said: "To see your child for the first time is extraordinary."
David Miliband also said he did not regret failing to challenge Gordon Brown for the leadership during the last Parliament.
He said: "It would have fractured the party and turned in on itself when we should have been addressing issues facing the country."'Won't win again'
On the election defeat, he added: "We lost the twin mantles of New Labour's dominance - fairness and change.
"Unless we get those back we won't win again."
The Milibands are the front runners in the contest, having both gained the support of more MPs than their rivals.
Neither would be drawn on the experience of running against a sibling.
Ed Miliband said of his brother: "He wants to win the best contest Labour can have and so do I."