David Miliband was warned today that he is running out of time if he ever wants to lead Labour - after he set out a dramatic vision for reforming the party headed by his brother Ed.
In his most high-profile intervention in domestic politics since losing the leadership contest in 2010, Mr Miliband called for "restless thinking" in a bid to win back power.
He set out a seven-point plan for reform, warning "Reassurance Labour" not to retreat to familiar comfort zones. "We will win again only when two conditions are met," he wrote in the New Statesman.
"First, that we fully understand in a deep way why the electorate voted against us in 2010. Second, that we clarify the kind of future we seek for Britain, and the means to achieve it, in a way that speaks to the demands of the time."
Mr Miliband was quick to praise his brother Ed, who endured a difficult start to the year before scoring a major success over Royal Bank of Scotland chief Stephen Hester's bonus.
But the intervention was described by supporters as a "reminder" he is ready to take over if Ed's leadership fails. They also fear he will only be able to take control if there is a change of leader in the next 12 months.
One said: "If that happens, the Labour Party will most likely decide that it picked the wrong Miliband brother and opt for the other one. Any longer than that, and there will be a feeling that it is time for someone else."
While there is no active plotting to topple the leader, another Labour source voiced concerns about how "disorganised" the party is.
After Labour opposed the Government's £26.000 benefit cap, the source added: "After the debacle we had this week on welfare reforms, we can't carry on like this."
Read More
Mr Miliband's article was joined by a call from former chancellor Alistair Darling for David to make a return to the shadow cabinet. "I would like him back on the front bench. For his knowledge, and his judgment," Mr Darling said.
"When I've seen him on various programmes talking about foreign affairs, he talks with authority. I understand his reluctance. There's always comparisons. He is probably right to take a raincheck. Certainly, he would be a gain."
