The late mail is: it's not a done deal VOTERS may want Anthony Albanese to head the ALP but the aspiring leader is facing a huge obstacle after yesterday's caucus ballot. Nobody can be certain about yesterday's numbers but estimates from all sides suggest Bill Shorten gained a lead of at least 10 votes. Optimists in the Shorten camp say it could be twice as much. Out of 86 caucus members, at least 48 were marked down as Shorten voters, even after taking into account the drift of a few members of the Right faction to support Albanese. The 48-38 outcome is a conservative estimate and assumes that several members of the Left disagreed with their factional colleagues and backed Shorten, a Right powerbroker. The tally could be more like 53-33, in the light of claims of a bigger shift to Shorten. Those from the Left who are said to have voted for him include Laurie Ferguson, Lisa Chesters, Maria Vamvakinou, Warren Snowdon, Brendan O'Connor, Kate Lundy and Julie Owens. While a few members of the Right (including Kevin Rudd and Justine Elliot) were said to have backed Albanese, this was not enough to neutralise the shift. On the whole, the caucus is voting along factional lines in a way not seen since the late 1960s. Every leadership contest in recent memory has seen a significant split in the Right. This was not only true in the fight between Julia Gillard and Rudd but also in those between (variously) Mark Latham, Kim Beazley, Simon Crean, Paul Keating, Bob Hawke and Bill Hayden. As one caucus member noted privately yesterday, this ballot is the first time since Gough Whitlam faced Jim Cairns in 1967 that the Right and Left factions are so neatly divided. Party historians might debate that point, but it is safe to say that Shorten won the day yesterday by at least 10 votes and probably more. That makes it very difficult for Albanese to secure enough support from Labor branch members to offset Shorten's advantage in the caucus. The maths work like this. Because the caucus members and branch members count as distinct voting blocs, each making up 50 per cent of the final outcome, an MP's vote is worth hundreds of votes from party members. The ratio depends on how many members fill in their postal ballots, but if 30,000 are lodged then each MP's vote is worth about 350 rank-and-file votes. A caucus ballot of 48-38 in Shorten's favour looks like a lead of 16,800 to 13,300 when translated into membership votes. In other words, Albanese is behind by at least 3500 membership votes before the membership count even starts. He would need to win about 17,000 of the 30,000 rank-and-file votes to take the leadership. . Albanese would therefore need to rally 57 per cent of the members to his side just to post a narrow victory over Shorten. The dream scenario for the Shorten camp is a caucus ballot of 53-33 in his favour. If that came to pass, Albanese would need about 63 per cent of rank-and-file votes to win. This isn't impossible. An online survey by Graham Young suggests 76 per cent of Labor voters prefer Albanese. Everything depends on how each side has been able to mobilise its branch loyalists to fill in their postal ballots. At this stage, however, the numbers are running in Shorten's favour.