Chris Williamson, the outspoken pro-Jeremy Corbyn MP, is booked to speak at a rally organised by the hard-left Momentum group at which Jackie Walker, currently suspended from Labour over allegations of antisemitism, is set to chair.
The Derby North politician is listed as one of the speakers at Momentum Thanet's People Before Profit rally in Kent on May 1, alongside Mark Serwotka, general secretary of the PCS trade union.
Also billed as speaking at the same event is Rebbeca Gordon-Nesbitt, who was selected as South Thanet's Labour parliamentary candidate despite having repeatedly defended Ken Livingstone over his suspension for comments about Hitler and Zionism.
She also questioned the “Zionist sympathies” of John Bercow, the House of Commons speaker, in a series of social media posts.
Mr Williamson's attendance at the event will raise further questions about his claim to be serious about ending the antisemitism crisis that has rocked Labour under Mr Corbyn.
Yesterday he appeared on Sky News and claimed he wanted to form "a cross-party consensus" to work on eradicating antisemitism.
But last month, Board of Deputies president Jonathan Arkush called for the whip to be removed from Mr Williamson after the MP said it was a “real pleasure and a privilege” to be sharing a platform with Ms Walker at an event in Peterborough.
Ms Walker's role as rally chair at the May Day Momentum event is also likely to spark further anger.
She had previously been removed from her position as national vice-chair of Momentum in October 2016 following widespread criticism of her comments about antisemitism and Holocaust Memorial Day.
She was suspended again by Labour in 2016 over comments in which she referred to Jews as being among the “chief financiers of the slave trade".
Earlier this month the JC revealed how Ms Walker had posted a bizarre "racial hierarchy" rant on Facebook in which she said people attending the Labour antisemitism demo in Parliament Square were "absolute enemies of Muslims, enemies of people of colour".
Ms Gordon-Nesbitt - a socialist historian who wrote a book praising Castro - was selected as the Labour Thanet candidate earlier this month.
She had previously posted on social media the claim that allegations of antisemitism against Ms Walker were "politically motivated."
And she also called the suspension of Ken Livingstone the result of attempts to "smear" Mr Corbyn.