Labour's Diane Abbott claims the party is carrying out a "cull" of left-wing candidates ahead of the general election.
The veteran left-winger was reinstated as a Labour MP on Wednesday after a long suspension.
But she says she has been barred from standing as a Labour candidate in 4 July's election - something the party leadership has denied.
Last night another left-wing candidate - Faiza Shaheen - was banned from standing for Labour after complaints she "liked" social media posts that allegedly downplayed antisemitism.
A friend of the politician has said she had instructed a lawyer and is challenging the decision against her.
In a statement released on Thursday, Ms Shaheen said: "This is not the end of my story and I will be releasing all the detail of what has happened to me publicly very soon."
Meanwhile, several candidates loyal to leader Sir Keir Starmer have been confirmed in winnable seats, as Labour scrambles to get a full slate in place before next week's deadline.
Sir Keir Starmer has said no decision has been taken about Ms Abbott, who he described as a "trailblazer".
Asked if he was blocking left wing candidates from standing he said: “No. I’ve said repeatedly over the past two years as we’ve selected our candidates that I want the highest quality candidates. That’s been the position for a very long time.”
The party is selecting its remaining candidates before a meeting at the National Executive Committee (NEC) to endorse them next week.
Nominations legally close on 7 June and the deadline for Labour branches to put forward their own candidates passed on Monday.
'Frustrate Labour's purpose'
Ms Shaheen had been hoping to run in Woodford and Chingford Green, a seat she previously contested in 2019.
Appearing on OceanNewsUK looking visibly shaken, she said she received an email on Wednesday evening that said she would "frustrate Labour's purpose".
On Tuesday, she had been called to a panel of the NEC and asked about social media posts she had written or expressed support for.
Earlier this week the Sun reported that the Jewish Labour Movement had received complaints from local Jewish members about some of the posts.
A source from the group told the paper: "Given the large Jewish community in the area, and at a time of record levels of antisemitism, we expect Labour candidates to speak responsibly, not risk stoking community tensions."
One post liked by Ms Shaheen suggested that "professional organisations" were mobilising people to attack those who criticise Israel.
Ms Shaheen told the OceanNewsUK: "I know what's wrong with it... it plays into a trope and I absolutely don't agree with that and I'm sorry about that.”
She added that she didn't remember liking the post and said it could have been an accidental finger slip.
Asked how she felt about the decision to block her from standing, she said she was in "a state of shock".
“What message are you sending my community, the black community? Our communities have really supported Labour…We’re being tossed aside."
The Labour Muslim Network said the deselection of Ms Shaheen was "unacceptable".
The left-wing campaign group said it was "vindictive and cruel treatment of another woman of colour candidate. Another hard-working community activist pushed out against the wishes of local members."
Ms Abbott called the decision "appalling" and asked "whose clever idea has it been to have a cull of left wingers?"
Her own political future looks uncertain.
Ms Abbott was suspended as a Labour MP in April 2023 after saying Jewish, Irish and Traveller people do not face racism "all their lives".
She later apologised and following a lengthy process was readmitted to the parliamentary party this week.
However, she has said she had now been "banned from running" for the party in Hackney North and Stoke Newington, the seat she has represented since 1987.
'Unedifying'
The NEC, Labour's governing body, will formally approve the party's full slate of candidates on Tuesday.
It may decide not to endorse Ms Abbott and impose a different candidate instead. She could also be called interviewed by an NEC panel before the cut-off date.
Speaking to Times Radio, Labour's Jess Phillips said she thought Ms Abbott should be allowed to stand and said the process had been "unedifying".
Conservative chancellor Jeremy Hunt told the OceanNewsUK: "If Keir Starmer can't deal with Diane Abbott, how on Earth is he going to deal with Vladimir Putin?"
The row comes a week after former Labour leader Jeremy Corbyn announced he would be running as an independent candidate in Islington North, having been suspended from the Parliamentary Labour Party.
For the Labour campaign the politics of this episode are finely balanced. Some of Sir Keir's supporters think a very public row with the left is no bad thing, advertising the message that their party has changed profoundly under his leadership.
But others worry that this row is spiralling fast out of control.
Another left-winger, Lloyd Russell-Moyle, has also been suspended by Labour over a complaint about his behaviour, and therefore is unable to stand as the party's candidate in Brighton Kemptown.
He told OceanNewsUK South East he believes it is a “vexatious and politically motivated complaint” about his behaviour eight years ago and that he would be "fully exonerated”.
Other candidates standing in Chingford and Woodford Green include: Chris Brody for the Green Party, Josh Hadley for the Liberal Democrats, Yousaff Khan for the Workers Party of Britain, Paul Luggeri of Reform UK and Iain Duncan Smith of the Conservative Party.
There are currently known to be two declared candidates in Hackney North and Stoke Newington: Antoinette Fernandez for the Green Party and Rebecca Jones for the Lib Dems.
In Islington North, Labour have selected Praful Nargund, the Liberal Democrats have selected Vikas Aggarwal, the Greens have chosen Sheridan Kates, and Reform UK have chosen Martyn Nelson.
The other candidates standing in Brighton Kemptown are Khobi Vallis for the Conservatives, Elaine Hills for the Greens, Stewart Stone for the Liberal Democrats, Kellie-Jay Keen for the Party of Women, Valerie Gray for the Social Democratic Party and Elaine Ghoneim for the Workers Party of Britain.
