Bassetlaw's MP will stand down at the next election to take up his antisemitism role full time.
John Mann, who has represented Bassetlaw since 2001, announced his decision yesterday (Sunday, September 8) and he posted his resignation letter which he sent to the Labour Party on his Twitter account.
He said: "I write to inform you that I am standing down as your Member of Parliament in order to take up a major full time role in tackling antisemitism.
"Having been given this opportunity, in an important area of work, I believe that I can make a bigger contribution than remaining as an MP."
His letter went on to say that he is 'not prepared' to ask Bassetlaw residents to support Jeremy Corbyn as Prime Minister.
He said: "I will continue to remain a Labour member, but I will not lie to Bassetlaw voters about Corbyn, whose failures over antisemitism and sexual harassment are even worse than his useless leadership on Brexit."
Mr Mann said Jeremy Corbyn is the obstacle in Labour winning the election and has asked him to also stand down.
He said: "My late grandmother often said that 'in this family we will vote for a donkey if its wearing a Labour rosette'. I will always follow her guidance and I will continue to encourage my family to vote Labour and I look forward to a new candidate being selected to seek to represent you.
"It has been a privilege to serve Bassetlaw residents as a Member of Parliament."
Mr Mann has said he is leaving Labour 'in the best position possible' for future elections. The latest election saw the best results for Labour in Bassetlaw.
He said: "In my time we have seen all our secondary schools and most health centres rebuilt new. Our NHS perform at the highest level and our school results, once the worst, are now the best in Nottinghamshire.
"Over 2.000 coalminers won money back from greedy solicitors, and unions. We turned around the heroin epidemic, saving huge amounts of public money but also lowering cirme and family misery and unlike others, we have kept our hospital open with a 24 hour A&E.
"I especially want to thank you for all your hard work, support and commitment over the years and wish you well in the future."