A new poll of Labour Party members and trade union activists has shown Ed Miliband in the lead.
The YouGov/Sunday Times poll (£) puts Ed Miliband on 51 per cent, with David on 49 per cent, once second preference votes are taken into account. On the basis of first-round votes only, David was four points ahead of Ed with 36 to his brother's 32.
Supporters of the former foreign secretary have been fairly confident of his victory for several weeks. An endorsement last week by the influential left-winger Dennis Skinner was a boost to his campaign, as it negated Ed's claim to support among the left of the party.
However, this poll suggests that the contest is still incredibly close. It seems that Ed may well emerge as the "compromise candidate", benefitting from second and third preferences in Labour's complex electoral college system. As long ago as June, a poll for LabourList showed that this could be the case.
The poll also shows a split in areas of support, with David being strongly favoured by MPs and MEPs -- gaining 41 per cent of their support to Ed's 29. However, the former climate change secretary leads among trade union members, gaining 36 points to his older brother's 29.
Interestingly, a separate YouGov poll for the Sunday Times of ordinary voters suggests greater public support for David, with 30 per cent saying that he would make the best leader, compared with 16 per cent for Ed. This is in keeping with the view expressed by many MPs that David is best equipped to take the fight to the Tories.
For the Miliband brothers, there is still everything to play for.