Kiri Allan says she will not stand again in the East Coast electorate at the election as she needs "time to heal myself and chart a new course for my life".
"I have let my electorate down, my party down, and all those that relied on me," she said in a statement on Instagram.
"Being the representative for the East Coast has been the greatest privilege of my life. But my actions have let everyone down."
Allan, who was arrested on Sunday after crashing a car on a waterfront Wellington road, said "many people have placed their trust and confidence in me as a political leader".
"I have failed all those that put their trust and confidence in me."
Police confirmed on Monday she had been charged with careless use of a motor vehicle and refusing to accompany a police officer, and will appear in court eventually. An infringement notice was also issued for excess breath alcohol between 250 and 400mcg.
Allan subsequently resigned from her ministerial roles and Prime Minister Chris Hipkins said she would take time to reconsider her political future.
The MP has been facing mental health problems in recent weeks and just returned from leave last week.
In her statement, Allan sent a message to Hipkins.
"I have undermined you and the trust you placed in me to do an important job for New Zealand. I cannot express the remorse I feel," she said. "I am so, so sorry.
"Second, to my colleagues and party members. I can't describe how full of anger towards myself for letting you all down. I am so, so sorry.
"Only a Labour led Government can deliver the strength and support our communities need. I pray my actions do not impact the political landscape - my actions were mine, and mine alone."
She also thanked the "awesome people" of the East Coast.
"Thank you for all your messages of love and support - I am so proud to have been your representative in Parliament, and I am so sorry to have let you down in a time when our region is hurting so much. I will continue to serve you as a MP until October and my offices are open with our arms wide open."
Allan said it was "time to step out of the arena".
"I'm not sure how long for, or if I'll return, but my focus is now on trying to find a different kind of strength to serve our people and our place."
Fellow Labour MP Willie Jackson on Tuesday said he didn't believe Allan should stand at the October 14 election.
"I think she needs to have a time out and come back another day," Jackson said.
He said he spoke with Allan on Sunday night before the crash happened.
"She wasn't good… If I'd been in Wellington it might not have happened," Jackson told reporters. "She rang me about 6pm, four hours before it all went wrong."
He added Allan was a "beautiful person" but was "sick and... she needs that support".
At his post-Cabinet press conference on Monday, Hipkins said Allan was offered more time off but said she wanted to get back to work.
"I made sure she had got support, that she had been seeing a counsellor ... I did not compel her to stay away from work."
He said Allan was very well-supported.
"Kiri had very good support from colleagues," Hipkins said. "We had arranged professional support for her. One of the conditions of returning to work is that she would continue with professional support."
Hipkins commended Allan's "bravery" for speaking openly about her mental health.
"When you are dealing with issues around mental health, that is incredibly difficult," he said.
"I don't take that lightly. I have taken it seriously from the beginning. I have been guided by feedback from Kiri about what will work for her.
"It is really tough. I commend Kiri for speaking openly. It is an absolute tragedy what happened yesterday. It is brave to speak openly, but it is not acceptable it got to that point yesterday."
