The latest MP to leave Labour has given a damning assessment of the party: I am leaving because of racism.
Dudley North MP Ian Austin became the ninth Labour politician in Westminster to quit Jeremy Corbyn's party in a week.
And he said the reason was racism.
Mr Austin has become infuriated with anti-semitism in the party, and feels its leader has not done enough to combat it.
He called it "the most difficult decision I have ever had to take" - and revealed he would not be following the likes of Chuka Umunna and Luciana Berger to the new Independent Group.
Speaking to the BBC, he said: "I have become ashamed of the Labour Party.
"I grew up listening to my dad teaching me about the evils of hatred and prejudice.
"One of the main reasons I joined the Labour Party, as a teenager here in Dudley more than 35 years ago, was to fight racism.
"I could never believe then that i would be leaving the Labour Party because of racism too."
Anti-semitism has become a major blight on Labour in recent weeks, and Mr Austin has struggled to hide his anger at times.
Mr Austin has been one of the more powerful politicians in the West Midlands in recent years.
His letter to constituents was particularly damning about the Labour leader.
It states: "I am appalled at the offence and distress Jeremy Corbyn and the Labour Party have caused to Jewish people.
"It is terrible that a culture of extremism, antisemitism and intolerance is driving out good MPs and decent people who have committed their life to mainstream politics.
"It is wrong that Luciana Berger has been bullied out of the Labour Party by antisemites. It is wrong that the party threatened Margaret Hodge when she spoke out on antisemitism, like they threatened me when I raised the issue with the party chairman.
"They had to back down because we had done nothing wrong, but the hard truth is that the party is tougher on the people complaining about antisemitism than it is on the antisemites.
"Jeremy Corbyn and the people around him have turned a mainstream party into something very different. He has spent his entire political career working with and supporting all sorts of extremists, and in some cases terrorists and antisemites. I always thought he was unfit to lead the Labour Party and I certainly think he is unfit to lead our country.
"I think Jeremy Corbyn and John McDonnell cannot be trusted with our national security and would undermine our democratic institutions.
"They supported the IRA when they were planting bombs and murdering people in shopping centres, hotels and pubs. They back totalitarian dictatorships like Venezuela abroad and echoed the Kremlin when Putin tried to murder people here in Britain.
"I respect people in Dudley. I always tell them the truth and I could never ask local people to make him Prime Minister."
As well as holding the West Midlands role when Labour were in government, he has also held the role of parliamentary private secretary to Gordon Brown when he was Prime Minister, working directly with him in Downing Street.
The other Labour MPs to leave this week were Chuka Umunna, Luciana Berger, Chris Leslie, Ann Coffey, Angela Smith, Gavin Shuker and Mike Gapes, followed by Joan Ryan who announced her departure late on Tuesday.
They were followed by Conservatives Anna Soubry, Sarah Wollaston and Heidi Allen, who have all joined the Independent Group.
Labour called for Mr Austin to quit as an MP and contest a by-election.
A Labour Party spokesman said: "We regret that Ian Austin has left the Labour Party.
"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."