A shadow minister is expected to launch legal action against the Labour Party on Tuesday, in a bitter row over the selection of a candidate for West Midlands Mayor.
ITV News understands that Naz Shah, Shadow Minister for Women and Equalities, will begin a legal dispute with her own party over the shortlisting of Salma Yaqoob.
Ms Yaqoob is the former leader of the Respect Party and ran as an independent candidate against Naz Shah in Bradford West in 2017.
The Labour MP claims Ms Yaqoob ran a "despicable" campaign against her, allegedly attacking her 'honour' and class, which Ms Shah says led her to consider suicide.
Ms Shah raised the issue at the weekly meeting of Labour MPs on Monday night, saying: "She (Ms Yaqoob) stood against us six times.
"She gave a platform for me to be 'hijab-shamed', which I can only equate to 'slut-shaming'. She is no socialist, this is George Galloway style politics."
Last week, Ms Shah took her concerns directly with Jeremy Corbyn at a meeting between BAME MPs and the Labour leader.
ITV News understands the legal challenge will centre on the fact that candidates normally have to be Labour members for two years before being selected, but Ms Yaqoob is understood to have only joined the party four months ago. In this case, the rules have been waived by Labour.
Two other groups of Labour MPs have also raised concerns, with both the Women's Parliamentary Labour Party (PLP) and LGBT+ PLP writing separate letters to the party about Ms Yaqoob's alleged behaviour.
The Women's PLP wrote, "Ms Yaqoob's campaign against Naz in the last general election should render her ineligible to hold party membership...it is, among other things, a disservice to her that the party might allow a woman who bullied and personally targeted her to represent us in an election."
In their letter, the LGBT+ PLP accused Ms Yaqoob of homophobia, including allegedly referring to being LGBT as a "choice of lifestyle."
Ms Yaqoob is an anti-war activist, whose candidacy has been backed by Momentum nationally, as well as other figures close to the Labour leader.
On the weekend, the Shadow Justice Secretary Richard Burgon tweeted a picture of himself alongside her at a Stand Up To Racism conference, describing her as "a courageous opponent of racism and war, who inspires people to fight for a better society based on justice, equality and socialism”.
On Monday evening Salma Yaqoob issued a statement on Twitter addressing the various allegations, which she described as either "false" or "seriously misleading".
"I want to be clear that I stand in full solidarity with the LGBTQ+ community and I am absolutely committed to confronting all forms of homophobia, bi-phobia and transphobia in our society," she wrote.
In relation to her election campaign in Bradford West in 2017, Ms Yaqoob has previously said: “I did not run or endorse a campaign of misogyny, patriarchy and clan politics. Even as a political opponent I showed [Naz Shah] respect as a woman and a public figure.
"As Shadow Equalities and Women Minister, I would hope she would welcome the principle of women coming forward for political office – even those she disagrees with. I am saddened that she is lobbying nationally to limit the right of local Labour members to make their own choice by seeking to remove me from even a potential shortlist."
ITV News has contacted the Labour Party for comment.