National's lowest ranked list MP Aaron Gilmore said it is with a "heavy heart" that he is to step down.
The National party wanted him to go over his antics during a boozy night in Hanmer and allegations he misled Prime Minister John Key's office.
Party president Peter Goodfellow was due to talk to Gilmore this afternoon. Goodfellow wanted a meeting tomorrow.
"After taking counsel from colleagues and family in recent days, I have decided that to stay on in Parliament would only serve to cause my loved ones more upset, and cause me undeserved further stress," Gilmore said in a statement.
"The media scrutiny has put me and those who are important to me under immense pressure with an attempt to discredit me. I have made mistakes. I am human. But the attacks on my integrity have started taking a toll on those around me and this is unfair on them."
Emails surfaced on Friday that lead to his contract ending at the the then Department of Building and Housing. Gilmore was due to attend a party conference in Whanganui at the weekend, but flew to Christchurch instead to spend time with his family.
Gilmore said he has told party whips of his intention to resign.
"I also want to make clear my support for the National Party and Prime Minister John Key remains unwavering," he said.
He apologised again to those he let down with his behaviour
"I'm determined to learn from those lessons as I continue my life with more grace and humility."
Gilmore had little option, once he lost the confidence of party leader John Key. He could have brazened it out, and continued as an independent MP if National had suspended or expelled him from caucus or from the party. But he has sensibly decided to make a clean break.
Had Aaron Gilmore shown grace and humility when this messy business first broke, he may have still had a political career. Today's decision however closes the page on ten days of anguish for Gilmore which he so easily could have avoided.