Ed Miliband will tomorrow issue his clearest political attack yet on his brother, David, calling on Labour to provide a "mandate for change" so that a "new generation" can lead the party out of its "New Labour comfort zone".
In a speech being distributed to as many party members as possible tomorrow, the younger Miliband brother will unashamedly draw stark dividing lines with the bookies' favourite, David, who is being portrayed by Ed's campaign as the party's "establishment" candidate.
The Ed Miliband camp said that tomorrow's speech "will say that the leadership election has come down to a big defining decision: whether to linger in the New Labour comfort zone and try one more heave for power, or to change to a new generation of leadership, beyond New Labour". It will seek to portray the fight between Ed and David Miliband as being between "change and continuity", respectively.
The "one more heave" reference is ironical, as it was frequently used by party modernisers who accused traditionalists of refusing to compromise with the electorate. In recent days, David Miliband has said that the party must escape from its "comfort zone" and appeal beyond its "core vote".
But on Tuesday Ed Miliband's team hit back, saying it was the "New Labour comfort zone" that must be shed. Tensions between the brothers' camps have heightened in recent days.
Ed Balls will also deliver a key campaign speech tomorrow in which he will say that the choice between a "head" candidate and a "heart" candidate is "false", and claim to be the "head-and-heart" candidate.
In his speech, Ed Miliband will say: "We must have the courage to change, the confidence to know that our values, when applied to the challenges of Britain in the modern world, can reconnect with those who have turned their backs on New Labour."
He will add: "We lost the last election but nobody won. The reason: neither New Labour nor Cameron's Tories had good enough answers to the challenges facing people in this country.
"I say to the Labour Party: 'I am not just seeking your votes. I am seeking a mandate to change -- to refound our party in ways which will reach out to those who have lost trust in us.'
"We must reach out to those who believe we have become cynical about our politics with our belief that it's politics which can bring people together to change Britain. We must reach out to the squeezed middle, those who find themselves working harder for longer for less, with a commitment to a new economy on the side of working people, rewarding businesses [which] invest in their staff and are committed to fair pay. And we must reach out to those who believe we became too casual about the liberties of individuals.
"Whenever a political party has become stuck in its ways there are always those who will fight to stay with what they know. The past can be a powerful anchor. Labour now faces a big, defining choice: whether to linger in the comfort zone of New Labour or whether to change, reach out to those who have lost trust in our party. Only change can win."