ReutersAndy Burnham cannot be a sitting MP and regional mayorAndy Burnham's return to parliamentary politics has automatically triggered an election to find a new mayor for Greater Manchester.
Sitting MPs cannot serve as regional mayors, because the regional role incorporates the role of police and crime commissioner.
The date for the Greater Manchester vote is 30 July.
Burnham, who won the Makerfield by-election for Labour with a 55% share of the vote, became the region's first directly elected mayor in 2017, and won two further terms in 2021 and 2024.
In 2024, he won 63.4% of the vote, with 420,749 voters backing him.
He won in every borough in the city region, including in Wigan, where the Makerfield constituency sits.
The cost of finding a new mayor to replace Burnham is estimated to be about £4.7m - which was one of the reasons Labour gave for blocking his bid to become its candidate in the Gorton and Denton by-election in February.
Burnham's win in Makerfield means voters there are set to go to the polls for the third time in three months when they chose a new regional mayor, having just voted in the local elections for Wigan Council in May.
Mayoral power
The mayor effectively chairs a cabinet made up of the leaders of all 10 boroughs of Greater Manchester.
This post incorporates the role of police and crime commissioner and managing the fire service.
As a result of the involvement in setting policing budgets and having influence over the force, MPs cannot sit in the role because of the inherent conflict of interest in them being responsible for making policing laws in Westminster.
The mayor also set transport budgets and have shared responsibility for the £6bn health and social care budget.
They also have involvement in the leadership of local NHS services, and control over the post-19 adult education budget.
It was under these powers that Burnham introduced free travel for 16 to 19-year-olds and a half-price pass for 18 to 21-year-olds.
Burnham also took control of the region's bus network under the integrated Bee Network brand.
The mayor oversees the Metrolink tram service, and it is envisaged that by 2030, all local rail services will be part of the network.
Burnham told a BBC North West debate for Makerfield by-election this could not legally be overturned by a future mayor.
As he made his victory speech at the by-election count in Wigan, Burnham said it would not have been possible for Greater Manchester to achieve everything it could without changes being made at a national level.
He is expected to launch a leadership challenge to Sir Keir Starmer once he takes his seat in Westminster.
He said: "It's with some sadness this result brings an end to my wonderful nine years as mayor of Greater Manchester.
"This city region has given so much to me, and it's a wrench to have to leave the job you love. But I'm not leaving the service of Greater Manchester.
"I've always been clear it can't achieve everything it should, and we can't close the north-south divide, and we can't make all the great northern cities be what they should be without big changes at the national level."
New voting system
On Wednesday, The Combined Authorities (Mayoral Elections) (Amendment Order) 2026 reintroduced Supplementary Vote (SV) in combined authority and combined county authority mayoral by-elections.
The next election will use the SV system, rather than the first-past-the-post system (FPTP) used by parliamentary elections.
Under the Supplementary Vote system, voters get to choose a first and second choice.
PA MediaPeople in Makerfield face their third election in three monthsIf no single candidate wins more than 50% of the vote share after first preference votes are counted, the top two candidates go into a run-off second round, in which second preference votes from the eliminated candidates are taken into account.
This system was in place for police and crime commissioners and mayors until 2022, when it was switched to FPTP, under which there is one round and the candidate with the most votes wins.
The Conservative government at the time argued that FPTP was a "fair and simple" system which ensured "clearer accountability".
The Electoral Reform Society has said that a SV election can have an impact on the nature of how an election is fought.
"Candidates can't just focus on the needs of their core electorate. Because of this, the Supplementary Vote encourages a more positive style of campaigning as candidates try to win the second preferences of voters outside their usual support base," it said.
Political parties now have just over one month to chose their candidates and campaign to win the regional mayoral election.
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