David Miliband is confirmed as the frontrunner - the poll suggests he would win the election if it was held tomorrow - but the details of the poll also suggest that the race is likely to go to the wire, with the Miliband brothers some distance ahead of their rivals.
YouGov has David Miliband leading on the first round of the electoral college, projecting the following totals.
David Miliband - 37
Ed Miliband - 32
Diane Abbott - 12
Andy Burnham - 11
Ed Balls 11
That is based on a 38-32 lead among party members on first preferences, and a 34-26 lead among trade unionists.
And that would take him to victory an electoral college run-off with his brother 55-45, though this depends not just on the polling but on the assumption that neither brother will have an edge among Parliamentary second preferences.
But the piece of information which the David Miliband team will emphasise and emphasise is that Labour voters think he is the potential leader most likely to win, with 52% of party members thinking that with his brother on 24%.
That is the key area on which Ed Miliband (or other candidates) must make a convincing counter-argument for their own merits over the next few weeks, or David Miliband's team should be able to go on to win, if they can use the poll to successfully continue to frame the race as a "head versus heart" choice.
Ed Miliband's task will be to give an account of a winning electoral strategy which demonstrates he would be a convincing "head and heart" option. That could be the crucial campaign battle, since other aspects of the poll show that Ed Miliband could be particularly well placed to pick up ground, perhaps particularly on second preferences. Party members see him as closer to sharing their political views.
One interesting detail is that Andy Burnham is perceived by party members as at least as left-wing as Ed Balls and Ed Miliband - indeed 24% think he is very or fairly left-wing, compared to 21 for Ed Miliband and 20% for Ed Balls (with David Miliband on 9% and Diane Abbott on 68%). 61% place Burnham as somewhere from slightly left-of-centre to left-wing with Ed Balls on 60% and Ed Miliband on 64%. (Diane Abbott is on 81% and David Miliband on 42%)
Those three candidates have very similar perceived centre-left positions among party members, 53% of whom place themselves as very or fairly left, and a total of 85% as somewhere from slightly left-of-centre to left.
The other piece of good news for David Miliband is that he is currently in first place among trade unionists polled, which is potentially the trickiest section of the electoral college. I am not sure of whether it has been possible to check those polled do have votes. The lead, which is much smaller than in polls of Labour voters generally, may partly reflect name recognition at this stage.
So David Miliband is the front-runner - but nobody would confidently call this election on the basis of tonight's poll.
How much could opinions change as the campaign reaches its final stages?
Quite a lot, if a YouGov poll of party members two months before the deputy leadership contest in 2007 is any guide. The poll fieldwork concluded on 28th April, with the results announceed on 24th June, and the first preference voting then was:
Hilary Benn - 36%
Alan Johnson - 19%
Peter Hain - 15%
Harriet Harman - 13%
Jon Cruddas - 10%
Hazel Blears - 9%
Harman, fourth and 23 points behind Benn with members at that stage, ended up the winner. Cruddas (fifth) topped the electoral college on the first round. Hilary Benn finished 4th.
The member preferences on the first ballot in the voting itself were Harman 24%, Benn 21%, Cruddas 17%, Johnson 17%, Hain 12%, Blears 9%.