The former deputy leader of the ACT party, Heather Roy, is leaving Parliament at the November election.
The Wellington-based list MP says she always planned to quit after three terms, which end in November.
Mrs Roy was ousted as deputy leader last year in a public row with the then leader Rodney Hide.
She also lost ministerial portfolios which she says interrupted some favoured projects, but says she still achieved a lot and is happy to go.
In announcing her farewell, she said it was important for new party leader Don Brash to have plenty of time to build a new team to pursue ACT policies for the election, and said Dr Brash played no part in her decision to go.
"I think it's really important that Don as the new leader has a group of people around him that he has real confidence in.
"He should be determining those people. I think he wanted me to be one of those - I felt that it was time for me to move on."
Mrs Roy does not yet know what she will do when her Parliamentary career ends.
ACT's leader Don Brash has paid tribute to Mrs Roy.
Dr Brash says Mrs Roy will continue to help ACT until November when she is due to leave.
Dr Brash praises her contribution so far and says he's very sorry to see her go but she will work closely with the party until the election campaign.