Keir Starmer has made it through to the final round of the Labour leadership contest, having secured the backing of shop workers’ union Usdaw. The party’s rules state that a candidate needs to get the backing of three affiliated organisations, of which two must be trade unions (or the nomination of at least 33 constituency Labour parties), and along with the earlier backing of Unison and Labour’s Environment Campaign SERA, Starmer has made it.

Usdaw also nominated Angela Rayner for the deputy leadership, and she is now also through to the final round of her contest.

This is a big week for nominations from affiliates, with both the GMB and Unite unions holding hustings with the candidates on Tuesday and Friday respectively. We are also expecting an announcement from CWU on its nomination, and Starmer is up against Rebecca Long-Bailey for the TSSA nomination. The deadline to secure either affiliate backing or CLP support is 14 February, so the other candidates do have a while, but the backing of this moderate union comes as a blow to Jess Phillips, who had also been hoping to get its nomination. With Starmer the clear frontrunner, there is a risk that many CLPs will nominate him as well (he is currently ahead on this measure too, with 11 nominations, while Long-Bailey has three and the others haven’t had any at all), making it much harder for Phillips – as well as Lisa Nandy and Emily Thornberry – to get onto the membership ballot at all.

If Nandy doesn’t make it through on the affiliate route (she has the NUM in the bag and is hoping for the GMB nomination), she might be able to surprise and impress members sufficiently to get their backing at CLP level, given she is currently not very well-known among the membership. Phillips and Thornberry are better known but members don’t seem to like what they see so far, meaning both are more reliant on MPs who’ve backed them persuading their CLPs to support them. This is by no means a given: not all Labour MPs, particularly those supporting Phillips, have enjoyed very good relationships with their local parties over the past few years and their support for a candidate could in fact deter members.

But it’s currently difficult to shake the impression that the leadership contest is heading for a two-horse race, and that many within the movement see a Starmer/Rayner top team as something of an inevitability.