Ahead of the Oldham West and Royton by-election, triggered by the death of long-serving MP and former minister Michael Meacher, discussion is beginning in Labour circles about who the party's candidate could be. Jon Lansman, a former adviser to Meacher and a director of the Corbyn-aligned group Momentum, has pledged not to run after the Sun reported that left-wingers wanted him to stand. He tweeted: "I rule it out 100% & no-one apart from you has been tasteless enough to suggest it to me at this point."

Lansman, a veteran of the Bennite struggles of the 1980s, is a feared figure among Labour MPs owing to his suppport for mandatory reselection. "When there are selections of an MP, I would like to see MPs who reflect the values of members of the party," he said recently. "The fact is that Liz Kendall got 4 per cent of the votes in the leadership contest." In response, one Corbynite MP told me: "Jon Lansman needs to wind his neck in and get back in his box. He's doing a lot of damage."

Jim McMahon is the potential candidate most often mentioned by Labour sources. He is the leader of both Oldham council and of the party's local government group. In 2014, he was named council leader of the year and received an OBE in the Queen's 2015 birthday honours. But some expect him to instead seek to become Mayor of Greater Manchester when the inaugural election is held in 2017.

Local councillor and former Oldham mayor Abdul Jabbar and fellow councillor Riaz Ahmad are other potential candidates having previously sought selection for the Oldham East and Saddleworth by-election in 2010. A shortlist of six candidates will be drawn up by Labour's NEC followed by a vote of the Oldham constituency party. Labour is currently 1/7 to hold the seat, which Meacher won with a majority of 14,738 in 2015, followed by Ukip on 4/1.