By Ian Dunt
Ed Miliband has urged Labour members to have "the courage to change" as ballot papers are filled in.
The papers, which arrived for Labour members last week, will be returned in time for the new leader to be announced just before the party conference.
"We must have the courage to change," Ed Miliband wrote to tens of thousands of members and supporters.
"We have to forge a new vision that appeals to the middle class voters we lost. And we must reconnect with the three million working-class people who abandoned New Labour as they felt New Labour abandoned them."
The email comes as Ed Miliband's camp desperately tries to secure his momentum in the race. The candidate, who enjoys the backing of Britain's major unions, won support from a Compass ballot and Pink News poll this week.
His brother is expected to win most support from the parliamentary party, but the battle for the membership is still alive and very hard to predict. In an interview with Labour List today, fellow-contender Diane Abbott said some polls put her second among members, just behind David Miliband.
Ed Miliband's camp were treating recent attacks on him from senior figures in the Labour party as a badge of honour, as part of the campaign's emphasis on breaking with the past.
"I have to ask the question, what difficult challenge has Ed put to the party, or to the electorate during the last three months, and I cannot think of one," former home secretary David Blunkett told the Guardian.
The comment inadvertently plays to the Ed Miliband campaign's strengths by fuelling the notion that the party's New Labour establishment is rallying against the campaign for change.
Alastair Campbell, Alan Johnson and Peter Mandelson have also made disparaging remarks about Ed Miliband in recent weeks.
Meanwhile, a Com Res survey for the Daily Politics found most Labour cpuncillors in the England and Wales backed David Miliband.
Thirty-three per cent of councillors backed David Miliband, compared to 26% for Ed Miliband. Diane Abbott came third with 21%.