Labour MP Lianne Dalziel is considering running for the Christchurch mayoralty this year and says that if she does she will resign from Parliament before the elections.
The Christchurch East MP has previously ruled out standing as mayor in the local body elections, due to be held in October.
If she ran, it would mean a byelection in her electorate, which has been a safe Labour seat and which she held with a 5334 majority.
However, the seat may not exist by the 2014 general election - her electorate was hardest hit by the Christchurch earthquakes and significant changes are likely when the Electoral Commission redraws boundaries this year.
She has reconsidered running "because people are desperate for a change".
Ms Dalziel also confirmed a report in the Press that she had asked Student Volunteer Army founder Sam Johnson to stand on her ticket as deputy.
But she said she did not yet have a running mate.