Jared O’Mara, the Independent MP for Sheffield Hallam, has said he is to resign as a Member of Parliament.
Mr O’Mara said he will step down in September, following Parliament’s summer recess.
The MP said: “Let everyone be assured that I will be tendering my resignation via the official parliamentary procedure as soon as term restarts.
“I reiterate my apology to my constituents, the people of Sheffield and the people of the UK as whole.”
Mr O’Mara had said he planned to take time out from his official duties to deal with “mental health and personal issues”.
On Saturday he issued a text message saying: “I’m not well and am in the process receiving medical help.
“I am not in any fit state to continue and nor would that be appropriate if I was.”
He was previously accused of treating his constituents with “inexcusable contempt” by his former press chief Gareth Arnold.
In one of a series of highly critical comments posted on Mr O’Mara’s Twitter account, Mr Arnold said: “Sheffield Hallam deserves so much better than you.
“You have wasted opportunities which people dare not to even dream of.”
A day after those comments, Mr O’Mara said: “I want to become a better person again; like I was. I feel I’ve become unrecognisable and I want to make amends.
“I need treatment for my mental health and rest first though.”
Mr O’Mara was also critical of his treatment by Jeremy Corbyn’s office and claimed there was a lack of support from the national Labour party.
In response, a Labour Party spokesperson said: “We take the welfare of our MPs very seriously and, while Jared is no longer a Labour MP, we are concerned for his welfare and we have continued to provide support to him, and will continue to do so.”
Mr O’Mara was elected as the Labour MP for the constituency in May 2017, ousting former Deputy Prime Minister Nick Clegg.
He now sits as an independent MP having quit Labour in 2018 after he was suspended over alleged misogynistic and homophobic comments posted online.