A string of tweets were issued from Sheffield Hallam MP Jared O'Mara's account on Tuesday evening, calling him "morally bankrupt".
The Twitter thread, which appears to have been posted by Gareth Arnold, begun saying: "Comms Team signing off... forever: Jared, you are the most disgustingly morally bankrupt person I have ever had the displeasure of working with. You do not care about your constituents. You do not care about anyone but yourself."
The thread went on to accuse Mr O'Mara of being in contempt of his electorate after refusing to stand down and call a by-election.
The MP was initially elected as a Labour representative, but resigned from the Party in 2018 following allegations of homophobic and misogynistic comments posted online.
The thread appears to have been written by staff member Gareth Arnold after signing it off with a link to his personal Twitter account, on which further tweets claimed it was "payback for all the nonsense I said to people defending you".
However, the validity of the Twitter thread has been called into question, as a Wikipedia page linked on Mr Arnold's Twitter account claims he has previously been known to run a fake account parodying far-right group Britain First.
The thread from Mr O'Mara's account continues: “Sheffield Hallam deserves so much better than you. You have wasted opportunities which people dare not to even dream of.
“Leaving constituents desperate for representation again. No matter if they are having their homes taken away, their liberties disgraced or being deported because of your inaction.
“My fear is that now (as I quit) the rest of the staff will leave and once again you will close your office and stop helping anyone but still take your wages until you have the decency to call a by-election.
“I cannot and will not defend you and your vile, inexcusable contempt for the people who voted you in. You selfish, degenerate p****."
The Twitter rant ended with a GIF of the Sheffield singer and Arctic Monkeys front man Alex Turner doing a mic drop.
Attempts were made to contact Mr O'Mara on Tuesday evening.