Labour former minister Kate Green has formally resigned as an MP, setting up a by-election in the safe seat of Stretford and Urmston in Manchester.
It comes after she was announced as Andy Burnham’s choice for Greater Manchester deputy mayor.
The Treasury released a statement to say it had accepted the Labour MP’s resignation.
It said: “The Chancellor of the Exchequer has this day appointed Katherine Anne Green to be Steward and Bailiff of the Manor of Northstead.”
Appointing an MP to the position is one of the formal mechanisms used to allow them to resign their office.
Metro mayors and their deputies cannot be an MP at the same time if their responsibilities include powers over the police.
Ms Green, a former shadow education secretary, is set to replace Baroness Bev Hughes, who announced on Wednesday she was leaving the role after five years.
Ms Green, who has been the MP for Stretford and Urmston since 2010, previously indicated she would not stand for re-election at the next general election.
She retained the seat, a Labour stronghold in the south-west of Greater Manchester, with more than 60% of the vote in 2019.
Labour leader Sir Keir Starmer tweeted: “Kate Green has been a tireless advocate for the people of Stretford and Urmston for 12 years.
“As the next deputy mayor of Greater Manchester, she will continue to deliver for her local community.
“Kate, I look forward to working with you in your new role.”