A by election will be triggered if a sitting MP switches political party.
If a sitting MP changes political party during the term of a parliament an by election in that constituency is automatically triggered .
Signatures
7
signatures
Government response threshold (10,000) · 7/10,000
Debate threshold (100,000) · 7/100,000
- 03 FEB 2026Petition rejectedduplicate
You may wish to sign the following petition, which calls for similar action: By-elections to be called automatically when MPs defect to another party https://petition.parliament.uk/petitions/737660
- 15 JAN 2026Petition created
Background
It seems indefensible for an MP to change political party and not allow the constituents to have the opportunity to endorse or otherwise that change.