Labour’s Burnham veto has made a tricky Manchester byelection much harder | Andy Burnham

When Labour dignitaries gathered at the Titanic hotel in Liverpool on Friday night, one question loomed above all others: to change captain or not?

For many, that question has become even more pressing after Keir Starmer’s allies brutally stopped Andy Burnham’s return to Westminster before it had even begun.

There were plausible practical reasons for blocking the Greater Manchester mayor from running in the newly vacant Gorton and Denton seat: not least that the byelection to replace him would be the biggest and most expensive in modern British history.

But many Labour MPs, including Burnham acolytes and agnostics alike, view the decision as a clear attempt to save the prime minister as the party heads towards a giant political iceberg.

This diverse south-east Manchester seat is home to about 119,000 people, including the left-leaning young professionals of Levenshulme, the white working-class Reform voters of Denton, and a significant Muslim population – 28% of the total – around Rusholme and Gorton.

Andrew Gwynne, the former minister who retired on medical grounds this week after an 11-month suspension over leaked WhatsApp messages, won with a 13,413-vote majority in 2024, with Reform UK finishing second.

Although it is a new constituency introduced as a result of boundary changes, it is formed from three seats that have voted Labour for decades. In Gorton, voters have elected a Labour MP since George V was on the throne.

Reform UK will run the byelection as a referendum on the government and Starmer in particular. Nigel Farage’s party has an eight-point lead in the national polls on average, while the prime minister’s popularity has tanked since the general election.

Four miles west, Labour will be pulled from the left by the Greens and any Gaza-focused candidate, whether that is an independent, a recruit for Jeremy Corbyn’s Your Party, or even George Galloway (yes, the 71-year-old has teased another comeback).

“The voters that are pissed off with Labour are liable to go in two directions,” said Prof Rob Ford, of the University of Manchester, pointing to the rise nationally of Reform UK and the Greens.

He expects Labour to lose without Burnham’s star power but said it would be tight, with “multiple forces pulling in different directions”.

Britain Elects, a polling firm, puts Farage’s party just one point ahead of Labour in Gorton and Denton, but this does not account for a host of nuances, including tactical voting.

Labour will hope enough voters are so repulsed by the thought of a Reform MP that they vote red, at the expense of the Greens and Lib Dems (which together accounted for a chunky 17% of the 2024 vote).

Polling suggests that “brand Burnham”, plus tactical voting, would put Labour four points ahead of Reform UK in Gorton and Denton, according to Ben Walker, of Britain Elects, who said that nationally a Burnham candidacy brings with it an additional five to seven percentage points.

Local factors make this trickier to decipher: Burnham is very popular in Greater Manchester, but Labour is heavily tarnished in Gorton and Denton as a result of Gwynne’s ill-advised text messages, which implicated several other local councillors, as well as Gaza and other national issues.

The other uncertainty is timing. The government has not yet set a date for the byelection but it is expected to be before 7 May, when Labour expects a battering in the devolved elections in Wales and Scotland and in councils across England.

Holding it at the same time pushes any byelection loss down the news agenda. Holding it earlier would untether Gorton and Denton from the national picture somewhat. Neither option looks great.

One thing is clear: choosing to contest the seat without Labour’s most popular politician has made an already difficult byelection much harder.