Unite pushes for de-selection of Labour MP Ian Murray
The Unite union is pushing to de-select Scottish Labour's Ian Murray as a candidate in the next general election.
The MP for Edinburgh South was Labour's only Scottish MP between 2015 and 2017 and has been a consistent critic of Jeremy Corbyn.
Party rules trigger a contest to replace an MP if a third of local members or affiliated unions back it.
But Mr Murray said installing a "hard left Marxist candidate" in his place would see Labour lose the seat.
He said he would now have to decide whether or not to stand as an independent candidate in the constituency.
A Unite spokesman said: "This decision was taken by Unite members following consultation with the relevant committees and branches of the union under our democratic processes.
"Our members are clearly concerned that Ian Murray has consistently undermined the Labour leadership in Scotland and at Westminster, and has on occasion attacked our union.
"No MP is entitled to their seat. It is for Mr Murray to now demonstrate why Unite members in Edinburgh South should return him as their representative."
Mr Murray vowed he would challenge the move.
The MP told BBC Radio's Good Morning Scotland programme: "If Unite want to try to de-select me on Thursday I am sure the membership of South Edinburgh - that I get on very well with and have their full, wholehearted support - will take a very dim view of and will vote accordingly."
Pressed on how he would respond to a move to replace him, Mr Murray added: "I think constituents deserve to have a choice of candidates in front of them, I would obviously discuss that with friends, family and colleagues to decide whether or not I would stand if I was deselected.
"But certainly I can guarantee that if the Labour Party ... put in some hard left Marxist candidate they won't win the seat of Edinburgh South.
"That would be damaging to the Labour Party and damaging to the country."
Mr Murray said he had not spoken to the Labour Party leadership about the move to deselect him.
Former Labour deputy leader Harriet Harman branded reports Mr Murray could be ousted from his constituency as "total madness".
Sources close to Mr Murray have said the de-selection efforts came from a central level at Unite, and not from the union's local branch.
The vote is due to take place on Thursday evening.
Before becoming an MP Mr Murray served as a councillor for the city's Liberton and Gilmerton ward from 2003 to 2010.
He also increased his profile by leading the campaign to save Hearts Football Club from administration.
Only Scottish MP
The Edinburgh University graduate was elected to Westminster in 2010 and, after an SNP landslide in 2015, he was Labour's only Scottish MP.
In 2017 Mr Murray retained his Edinburgh South seat with 54.7% of the vote.
He also increased his majority to 15,514 (32%) - the largest in Scotland.
In February he declined to join seven Labour MPs who left to form an independent group in protest at the party's approach to Brexit and anti-Semitism under Jeremy Corbyn.
At the time Mr Murray said Mr Corbyn should "listen and learn and decide if he wants to keep the Labour Party together".