Jeremy Corbyn was today braced for further walkouts as Labour MPs rallied around their former colleague Ian Austin.
The Dudley North MP quit Labour this morning, saying he had become "ashamed" of the party due to its lurch towards the hard left and its failure to deal with anti-Semitism under Mr Corbyn's leadership.
More coverage from the Express & Star
Express & Star comment: Labour Party in a sorry state
Peter Madeley: Labour Party turning into closed shop under Jeremy Corbyn
His decision has prompted a wave of support from MPs, with Labour deputy leader Tom Watson saying Mr Austin's departure was "a serious blow" to the party, and Pat McFadden describing it as "a wake up call".
Labour has called for Mr Austin to resign as an MP and contest a by-election.
Mr Austin, who became the ninth MP to leave Labour when he revealed his decision in the Express & Star, says he has no plans to join the Independent Group consisting of eight Labour MPs and three Tory defectors.
West Bromwich East MP Tom Watson has said he believes that unless the party changes there may be more departures.
"I'm deeply saddened to read of Ian's decision to leave the Labour team in the Black Country," he told the Express & Star.
"He has served the Labour Party for nearly 30 years and is one of the hardest working MPs in the UK. I didn't want him to go, not just because he is a friend but because Labour needs people of his experience, calibre and passion if we are to win.
"There is no point in denying that his departure is a serious blow to my party. His resignation ends a week of turmoil in British politics that we must all reflect on."
Wolverhampton North East MP Pat McFadden, said: “Ian is a great friend and a brilliant local MP. He has been in the Labour Party his whole adult life.
"It is completely tragic that he has concluded he has to leave the Labour Party. He has spoken out strongly and bravely about anti-Semitism and been a great campaigner for the people of Dudley.
"If the loss of great MPs like Ian isn’t a wake up call, I don’t know what would be.”
Emma Reynolds, the MP for Wolverhampton North East, said: “I am deeply saddened to hear that my colleague and friend, Ian Austin MP, has decided to leave the Labour Party.
"I have the utmost respect for Ian. He is a fantastic MP. His work in Parliament and in Dudley is hugely impressive. He is such a strong voice for the Black Country and a dedicated campaigner against racism and anti-Semitism.”
Deeply saddened to hear that my colleague & friend @IanAustinMP is leaving Labour Party. I have utmost respect for Ian: a fantastic MP - impressive in Parliament & his constituency, a strong voice for the Black Country and a dedicated campaigner against racism & anti-semitism. https://t.co/naKxyzCXOC— Emma Reynolds (@EmmaEReynolds) February 22, 2019
Birmingham MP Khalid Mahmood said Mr Austin's decision was "very sad", but added that Labour was attempting to tackle anti-Semitism.
"I have known Ian a long time, before we were MPs and he has been a good friend. It’s regrettable that he’s done this,” he said.
"Unfortunately there are those associated with the party who make comments. But the party is doing its best and will continue to have zero tolerance against anti-Semitism.
"On that basis, we should move forward, together. We are a family – I have very high regard for Ian, but this is very sad."
Labour MPs who have left the party over the last week to join the Independent Group have praised Mr Austin for his decision.
Chuka Umunna said: "Massive respect to Ian Austin for making this incredibly difficult decision – it’s painful and hard but he has stayed true to his values and what he believes to be the national interest."
Mr Leslie added: "Full respect for Ian Austin and his difficult decision to leave Labour today. Politics is broken and it is so important MPs stand up for the mainstream values we share."
And Luciana Berger tweeted: "I fully understand why Ian Austin has come to this difficult and painful decision."
Angela Smith said she was "thinking of my good friend Ian Austin, who I know has made a brave but painful decision to leave the Labour Party".
Mike Gapes said: "Well done Ian Austin. I know how hard it is to make the very difficult decision that you can no longer be a member after decades of work for the Labour Party. Politics is broken."
Mr Corbyn has called for all Labour defectors to stand for re-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 to do is to resign his seat and let the people of Dudley decide who should represent them."
Dudley Council leader Councillor Qadar Zada told BBC WM he is disappointed at the decision of Mr Austin to leave Labour and thinks he should trigger a by-election.
Express & Star readers have joined the debate online via Facebook and Twitter.
Head to the Express & Star Facebook page for more reaction
Colin Peplow said: "Fair play he has gone with what the people wanted him to do."
Another reader added: "Now the decent thing for him to do is resign from Parliament because he won that seat on Labour's manifesto."
The Bishop of Dudley, Graham Usher, also gave his reaction, tweeting: "My prayers are with Ian Austin and his family. As a Member of Parliament, Ian has championed the people of Dudley North and stood firmly against racism and anti-semitism."