Members of the Falkirk West Constituency Labour Party (CLP) are expected to bring forward a motion of no confidence in Stephen Deans's leadership at a meeting on Sunday.
Sources at the local party, which Mr Deans has chaired for the past year, were doubtful he and many of his supporters would attend the meeting, to take place at Camelon Labour Club.
However, they were confident a majority would vote to replace him even if the controversial Unite official chose to defend his role in person.
Mr Deans quit his job at the Ineos plant at Grangemouth on Monday. He was alleged to have used work time for local Labour Party business rather than legitimate trade union activity in his role as Unite convener at the plant. Mr Deans is also the chairman of the Unite union in Scotland.
A key figure in the Falkirk West CLP said: "I would expect Stevie Deans's chairmanship to be challenged. I'm quite sure there will be a challenge.
"I really don't think the members want to carry on with Mr Deans. A lot of people are very unhappy and have been for a long time, before everything came to a head at Ineos."
Another local party member said: "I can't believe he will have the stomach for fighting for control of the party when there is now no chance of installing his preferred candidate to fight the next election.
"Unite have had their fingers so badly burned I think he will do the honourable thing and step down before Sunday."
Mr Deans helped recruit a large number of new local party members, many who worked at Ineos, in a bid to have Unite's preferred candidate, Karie Murphy, selected to fight the Falkirk seat at the next election.
Both were suspended by Labour over the move but reinstated after witnesses withdrew evidence during an inquiry.
A separate Ineos probe into Mr Deans's activities sparked a wider dispute over the firm's plan to freeze wages and cut pensions. Unite backed down after Ineos threatened to close the petrochemical side of the plant.
Sunday's scheduled CLP meeting will be attended by a UK Labour official, as the local party remains in "special measures," barred from drawing up its own candidate shortlist.
The prospect of a challenge emerged as a war of words broke out between David Cameron and Len McCluskey, with the Unite leader demanding an apology for the Prime Minister's "disgraceful slur" on Mr Deans, whom he branded a rogue operator who had almost singlehandedly brought down Scotland's petrochemical industry.
At Prime Minister's Questions, Mr Cameron challenged Labour leader Ed Miliband to reopen the party's inquiry into alleged vote-rigging within the Falkirk Labour Party.
He said: "We have a real problem with a rogue trade unionist at Grangemouth who nearly brought the Scottish petrochemical industry to its knees. We need to have a proper inquiry; a Labour inquiry."
But the Prime Minister's remarks prompted a furious response from the Unite General Secretary. He called the comments an abuse of parliamentary process "in a naked attempt to gain political advantage from events at Grangemouth".
Mr McCluskey said Mr Deans was a "decent man" who served thousands of working people for 25 years.
He said: "The Prime Minister's rush to smear a good and honourable man will appal decent-thinking people. It dishonours the office he holds and he should apologise at once".
This week Tory backbencher Henry Smith wrote to Police Scotland asking it to reopen its investigation into vote-rigging allegations in Falkirk, dropped because of lack of evidence, after a leaked dossier of 1000 emails claimed Unite had plotted to undermine Labour's own probe into the claims.
However, a Police Scotland spokesman denied a full probe had now been launched but, rather, the force's economic crime unit was looking into the material sent to it to see if there was any suggestion of criminality, which would lead to a probe.