Jack Straw has endorsed David Miliband for the Labour leadership election, telling voters he welcomes the shadow foreign secretary's enthusiasm for defending New Labour's "terrific" record.
Mr Straw nominated Diane Abbott for the leadership election because he wanted to see "the widest possible debate" in the election.
After three months of campaigning he has backed David Miliband for the party's eventual leadership, however, calling him an "outstanding candidate" who has "the qualities necessary both to be leader of the opposition and then prime minister".
"He has the strength and the depth to stand up to David Cameron at prime minister's questions week after week, and he can stand up for the people who will be most badly hit in our communities by the policies of this Con/LibDem government," he wrote in an article on his blog.
Among the seven reasons Mr Straw listed explaining his support for Mr Miliband was the shadow foreign secretary's determination to defend Labour's policies.
Mr Miliband's reluctance to move away from Labour's 2010 general election manifesto has differentiated him from his brother, Ed Miliband, and helped attract the support of Mr Straw.
The shadow justice secretary, one of the longest serving members of the New Labour Cabinet, added: "We won't get anywhere if we stand on our heads and start undermining what we achieved in government. Our record was overall a terrific one."
Mr Straw acknowledged some of the weaknesses of the Labour government in a telling admission.
He wrote: "At the same time as standing up for our achievements, David has not been afraid to learn from the mistakes which, inevitably, all governments do make - not least in the style of leadership that did not give sufficient prominence to the party, or to parliament."
Voting begins on September 1st, with new members able to join the party to vote until September 8th. The result of the five-way race - which sees the Miliband brothers facing challenges from Andy Burnham, Ms Abbott and Ed Balls - will be announced on September 25th.