David Miliband has won the support of John Cruddas in his bid to become Labour leader, while his brother Ed has secured the backing the New Statesman and Ed Balls has been endorsed by former London mayor Ken Livingstone.
In an interview with the New Statesman Cruddas said he was giving his backing to David Miliband because he was the only candidate in the race advocating "communitarian politics".
The Labour MP for Dagenham, who stood in the party's deputy leadership campaign in 2007, said that while he had disagreed with Miliband on a lot of policy matters he was impressed with the former foreign secretary now that he was "unburdened by office" and free to speak his own mind.
"We see it around issues of party reform, devolution and local government, and around the question of national identities within Labour," he said.
And writing in the Daily Mirror today Cruddas said that David Miliband had "the patience, the strength and the convictions to get the public listening".
"He can lead a credible opposition and build a party that is united for the first time in a decade," he said.
And in what may be seen as an attack on the other Miliband in the race, Cruddas told the New Statesman: "He's not just attacking the Liberals, as some of the others have."
Shadow energy secretary Ed Miliband has been particularly critical of the decision by the Lib Dems to enter into a coalition with the Conservatives and has said he would demand the resignation of Nick Clegg before considering any future alliance with the deputy prime minister's party.
The younger Miliband has won the support of the New Statesman itself, with the magazine calling for a "bold, charismatic, compassionate and visionary leader" for the party.
The monthly politics magazine argues: "It is Ed Miliband who has been most prepared to challenge New Labour orthodoxies, to use a different kind of language. He advocates a Labour agenda that is confident, forceful and empowering, committed to greater freedom, social justice and, above all else, reducing inequality.
Adding: "Ed Miliband also understands that the Labour Party must once more become part of a much larger and wider movement for change - a true movement, transcending class divisions and geographical boundaries."
Meanwhile the other Ed fighting to be Labour leader, Ed Balls, has secured the endorsement of former London mayor Ken Livingstone.
Livingstone said that Balls was someone who could "really get things done" in government.
In a letter to party members he said: "He’s Labour through and through and is committed to strengthening the trade union link. And he’s shown over the last few months that he is the candidate best placed to shorten the life of this Tory-Lib Dem government."
"After the damage he’s caused to Michael Gove over the school buildings fiasco just imagine what he could do once he gets stuck into Cameron and Clegg."
He added: "I believe Ed Balls has the strength of character to do the top job, to stand up for what he believes in and not get knocked off course by the Tories or the right-wing press.
Livingston's rival for the Labour London mayoral nomination Oona King has backed Ed Miliband in the leadership race.
Balls will be speaking at a event hosted by the Independent's chief political commentator Steve Richards at a Demos/Open Left event in Canary Wharf this evening.
The ballot for the new Labour leader opens on Wednesday September 1, with the winner announced at the start of the party's conference in Manchester on September 25.
Dods Parliamentary Communications Ltd