Ian Austin has become the ninth MP to quit Labour this week, blaming leader Jeremy Corbyn for “creating a culture of extremism and intolerance”.
He told stated the leadership had failed to tackle anti-Semitism and had turned the party into a “narrow sect”.
Austin holds a majority of just 22 in his 71.43% Leave voting constituency of Dudley North.
The MP for Dudley North said he had no plans to join the new Independent Group of former Labour and Tory MPs.
Labour deputy leader Tom Watson said it was a “serious blow”. The party called on Mr Austin to face a by-election.
A spokesman expressed regret about his decision but said: “He was elected as a Labour MP and so the democratic thing is to resign his seat and let the people of Dudley decide who should represent them.”
News of Mr Austin’s resignation was first broken by the Express & Star newspaper.
The MP stated that his “work for the people in this community is going to carry on as it always has”, and that he had been an open critic of Mr Corbyn when he was elected in 2017.