National list MP Claudette Hauiti has decided to withdraw from the election and politics altogether.
She has already been selected as National's candidate in the Kelston electorate, which is thought to be a safe Labour seat.
She told National MPs at their caucus meeting this morning.
Her decision comes a few days before National releases its list ranking and Ms Hauiti may have been warned she would get a low list ranking.
She recently returned her parliamentary credit card after using it for personal spending.
The former broadcaster stood in Mangere last election, won by Labour.
She didn't become an MP until May last year when National list MP Aaron Gilmore resigned.
Ms Hauiti said in a statement it had been a difficult decision and she was announcing it with regret.
"I wish to thank the National Party for the opportunities that been given to me to be part of a stable, effective government that has been good for New Zealand and will, I am sure, continue its good work after the general election on 20 September."
National Party president Peter Goodfellow thanked Ms Hauiti for her contribution to the party.
National would reopen nominations for the Kelston electorate on July 23, for a shortened period closing on July 30.
"I expect a board selection panel, drawing on local electorate input, will meet to make a final decision by early August," Mr Goodfellow said.
It was the same process as was followed in 2011 when National MP Simon O'Connor was elected to Parliament in Tamaki after the late withdrawal of Allan Peachey.
New Zealand First leader Winston Peters called it a National Party cover-up.
"That's as plain as day and night. She has had you believe that she has resigned. She is just not standing again at the election. That is not accountability.
"She's standing down without any accountability from the National Party, the whips or the Prime Minister."
He said the National Party should reveal how much money Mrs Hauiti misspent.
"I don't believe it was $200 for a start. You try and have an overseas trip on $200.
"They throw allegations around at everyone else. When it comes to themselves, there's no accountability at all. They thought they could do a snow-job and say nothing at all."
- additional reporting Derek Cheng