Northern Mayor Jamie Driscoll's campaign manager has been kicked out of the Labour Party over links to a Marxist group, the Mirror understands.
Tony Pierre, hired by the North of Tyne Mayor just a few months ago, was found to have been a member of Socialist Appeal - an openly communist organisation banned under Labour's rules. It is not clear whether he continues in his role.
Northumberland councillor Holly Waddell, another figure said to be close to Mr Driscoll, has also been expelled by Labour for the same reason.
Labour Leader Keir Starmer was accused of launching a purge of Left-wingers loyal to former Leader Jeremy Corbyn when he banned Socialist Appeal and three other groups last year, which either openly promoted communism or claimed anti-Semitism allegations against the party were overblown.
Those banned included Resist, Labour Against the Witchhunt and Labour In Exile, which expressly welcomes expelled or suspended members.
The openly-Marxist Socialist Appeal also became a forbidden group, and anyone found to be a member when the rules changed last year faced auto-exclusion.
The news comes after shock news that long-serving Newcastle City Council leader Nick Forbes - a close ally of Labour Leader Keir Starmer's and part of the Shadow Cabinet - had been ousted as the candidate in his council ward by local Labour members, with some sources pointing the finger at activists loyal to Mr Driscoll.
The Mayor remains one of the few remaining figures who backed former Leader Jeremy Corbyn who has succeeded in retaining a high-profile position. However, it is said he faces a battle to be reselected as the party's candidate in 2024.
The 51-year-old was elected in 2019 with 56% of the vote for a five-year term.
Part of Mr Pierre's role was drum up support among party members in the North East.
A Labour source said: "Tony Pierre has picked so many arguments within the Labour Party it’s hard to believe he even wanted a Labour Government.
"But now questions need to be asked again about who mayor Jamie is associating with and whether he is going to drop Tony as a result."
Mr Pierre and Councillor Waddell have both denied being members of Socialist Appeal.
Coun Waddell said: "It is my belief that the party have mistakenly taken likes from my personal Facebook page as an endorsement of a group proscribed by the Labour Party, Socialist Appeal.
"I am not and have never been a member of the organisation, nor have I supported it in any sense. I have never bought their paper, attended any events or given them financial support. I was shocked and saddened by this decision which I will be appealing."
The Labour Party declined to comment.
It is the latest in a series of clashes between Labour leader and MPs and activists.
Last week, the leader's office threatened to suspend 11 MPs who signed a Stop The War coalition letter which accused NATO of "eastward expansion" in response to Vladimir Putin's attack on Ukraine.
The leader told a meeting of the Parliamentary Labour Party people who drew a "false equivalence between the actions of Russia and the actions of NATO" would have "no place" in the party.
Separately, Labour suspended funding for Young Labour and suspended the youth wing's conference. It comes after Young Labour accused the leader of “backing Nato aggression”.
