Chesterfield MP Toby Perkins has come out in support of Labour's deputy leader Tom Watson - after he faced a barrage of criticism online for saying the party needed to do more to tackle anti-Semitism.
Writing in the Observer over the weekend, Mr Watson warned that Labour may 'disappear into a vortex of eternal shame' and render itself unfit to lead if it does not combat anti-Semitism - which is prejudice against or hatred of Jews.
He also urged Labour leader Jeremy Corbyn to adopt all the examples in the International Holocaust Remembrance Alliance definition - and called for internal inquiries into Jewish Labour MPs Margaret Hodge and Ian Austin to be dropped.
Mr Watson wrote: "This is one of those moments when we have to take a long, hard look at ourselves, stand up for what is right and present the party as fit to lead the nation - or disappear into a vortex of eternal shame and embarrassment."
On social networking site Twitter last night, many people called for Mr Watson to resign - with #resignwatson the top trending topic in the UK at one point.
Writing on Twitter, Mr Perkins said Mr Watson was right 'on all counts' and described #resignwatson as a 'virtual cesspool'.
He added: "Aside from what the ongoing anti-Semitism row says about our party, it’s unforgivably amateurish that we are allowing our problems to dominate the agenda when the Government should be under the cosh for Brexit, NHS, Universal Credit etc."
Mr Watson said: "It sometimes feels like people have been calling for me to stand down from day one but I never, ever thought I'd be facing demands to #resignwatson for standing up for people who are facing prejudice and hate."
In a video message posted on Twitter yesterday, Mr Corbyn said: "People who use anti-Semitic poison need to understand: you do not do it in my name or the name of my party. You are not our supporters."
Mr Corbyn has repeatedly condemned anti-Semitism.