Makerfield by-election set for June 18 as Burnham runs to enter Commons and trigger Starmer leadership challenge

A Westminster by-election in Makerfield (Greater Manchester) was confirmed for June 18, 2026, and has become arguably the most consequential UK special election in years because of its direct link to Prime Minister Keir Starmer's leadership. The seat was vacated when Labour MP Josh Simons announced his resignation on May 14 and was appointed Crown Steward and Bailiff of the Chiltern Hundreds on May 18, deliberately clearing a path for Andy Burnham, the Mayor of Greater Manchester, to enter the Commons.

Labour's National Executive Committee certified Burnham as candidate on May 19, bypassing local selection. The mechanism matters: Labour rules require leadership candidates to be members of the Parliamentary Labour Party, so Burnham must first win a seat before he can mount a challenge to Starmer.

A Survation poll conducted May 26-June 1 put Burnham (Labour) on 49% and Reform UK on 39%, a 10-point lead, up from a tighter 43-40 margin in a May 18-22 poll. The by-election unfolds against the wider 2026 Labour leadership crisis: more than 95 Labour MPs had by mid-May called on Starmer to resign or set a departure timetable, and former minister Catherine West (on May 9) threatened a leadership challenge — needing nominations from 81 MPs (20% of the roughly 403-strong PLP) to force a contest — though she was branded a 'stalking horse.' Notably, Starmer's large Commons majority means no parliamentary no-confidence vote is in prospect; the threat is intra-party.