Mr O’Mara, who was reportedly arrested on suspicion of fraud earlier this month, has endured a turbulent two years in office since ousting Nick Clegg from his seat in the 2017 General Election.
The Star exclusively revealed he intended to resign following the MPs’ summer recess, which is due to end on Tuesday, September 3 but some constituents had cast doubt as to whether he would actually stand down.
Now, a Treasury spokesman has confirmed it has received ‘short contact’ from Mr O’Mara confirming his intention to resign.
He said: “He has contacted the Treasury and stated his intention to resign in the form of a short contact.
“But an MP cannot directly resign their seat and that dates back to 1624. They apply to be appointed to either the Crown Steward and Bailiff of the Chiltern Hundreds and the Crown Steward and Bailiff of the Manor of Northstead.
“It’s the Chancellor who appoints MPs to these offices. A warrant gets served and then they get appointed to one of these offices and then that’s the process by which you resign.”
The spokesman added that the ‘contact' stated he intended to stand down on September 3 and that the process cannot begin during the MPs’ summer recess.
The Star understands that Mr O’Mara was arrested along with his chief of staff Gareth Arnold – who, it is alleged, was arrested on suspicion of conspiracy to commit fraud.
Police officers are said to have raided the MP’s constituency office, removing documents and computers for investigation on Friday, August 16.
In a statement, South Yorkshire Police said: “We neither confirm nor deny the identity of someone who is or is not subject of investigation.”
Neither Mr O’Mara or Mr Arnold could be reached for comment.
The arrest allegations are the latest revelations in a troubled time in office for the Sheffield Hallam MP.
In July, Mr Arnold resigned by posted a damning rant on the MP’s own official Twitter account .
A 20-year-old woman also accused the politician of sexual harassment during the same week.
Mr O’Mara then stated he was ‘not well and in the process of receiving medical help’ and would resign following parliament’s summer recess.
In April, the politician closed his constituency office for a month and there were reports all his staff were either sacked or walked out, and he stopped holding surgeries or responding to correspondence.
He also quit the Labour Party after being suspended over historic misogynistic and homophobic comments made online.
Dr Felicity Matthews, a senior politics lecturer at the University of Sheffield, said a by-election to replace Mr O’Mara could be held as soon as October.
She said: “You could be looking at a by-election by the end of October and that’s interesting in itself because I live in Sheffield Hallam and the Lib Dems have been out since it lost its seat in 2017.
“It’s going to be a real bitter battle and Labour were not able to publicly campaign against Jared before his resignation and even now it's going to be interesting.”