Ballots are open in the Labour leadership race and voting is underway. Can anyone stop Keir Starmer?

The Fire Brigades Union certainly hope so. As Sienna Rodgers reveals over at LabourList, the FBU has filmed a number of negative adverts attacking Starmer and Lisa Nandy. The first in the series, which was released last night, condemns the two for their role in the 2016 attempt to remove Jeremy Corbyn from the leadership.

There's long been a debate within the Corbynite camp about how to approach the post-Corbyn world. The first school of thought, held by Jon Lansman, who is Long-Bailey's campaign chief, and to a great extent Rebecca Long-Bailey herself, is that Corbynites must build alliances to their immediate right in order to avoid a repeat of the 1980s, when the Labour left found itself marginalised and excluded.

That approach means that you support Angela Rayner over Richard Burgon, because while Rayner might not be one of you, she is guaranteed to win and is at least semi-sympathetic to the overall project.

The second strategy, favoured by the FBU's general secretary Matt Wrack and others within Momentum's leadership, is to opt for a far more negative approach. This involves reminding Labour members about the coup against Corbyn, going after the other candidates over their donations and their evasions and much else besides. It means favouring Richard Burgon over Angela Rayner for the deputy leadership, even though he is not going to win, because his commitment is not in question.

Though Long-Bailey has largely opted to pursue the first approach, her campaign has, in practice, ended up opting for a bit of both to no good effect. Now some of its allies in the trade union movement have opted to go freelance in order to pursue the latter strategy without interference.

The problem is that you can't convince people that Starmer and Nandy are beyond the pale while your preferred candidate is at the same time pledging to offer them both shadow cabinet roles, or to serve in their shadow cabinets if asked. It's incoherent and won't work.

Team Starmer's fear is that it might work so badly that another candidate benefits. While many of Starmer's allies fear that dirty tricks might yet see the contest turned on its head, their big preoccupation is still what happens if Starmer doesn't win outright – and if Nandy, not Long-Bailey, is in second place.

Nandy has an excellent second-preference strategy: she is far and away the candidate picking up the most second-place votes. But her problem is that she doesn't have enough first preference votes to make it into the final round. If Long-Bailey's allies final throw of the dice blows up in their candidate's face, they might succeed in stopping Starmer: but it could be that Nandy, rather than the shadow business secretary, is the beneficiary.