Former Labour finance minister Leo Brincat is openly urging party delegates not to vote for general secretary Jason Micallef in next week's election of party executives, saying the MLP must avoid making such "risky and counterproductive choices".
In a letter published in this newspaper today, Mr Brincat does not mention Mr Micallef by name, but he speaks of a particular exchange which, several Labour sources say, took place between him and the general secretary.
"When I recently expressed my opinion (and that of many delegates who have supported Joseph Muscat throughout the leadership campaign), to a key official, that his position had become untenable in the wake of the electoral defeat analysis report, I was impolitely told that when the time comes and I am proven wrong I should not even bother to congratulate him," Mr Brincat writes.
"This is the kind of arrogance that I hope delegates will push aside," he continues.
Mr Brincat also says that some of the arguments put forward by certain incumbents to try to hang on to their post "offend one's intelligence".
"They ran as follows: If I am not elected I risk ending up without work. I am more or less the same age as the party leader. I apologise for past mistakes. I will mend my ways. I still have much to contribute to the party. And on, and on, and on."
When contacted, Mr Brincat declined to comment further, saying he had nothing to add.
Labour sources told The Sunday Times an exchange between the two took place a few weeks ago when Mr Micallef asked for Mr Brincat's opinion on his intention to stand again for the post (it had not yet been officially announced).
"Leo told him, you want me to tell you what I think or what you want to hear," a Labour source said about the conversation which has now become something of an open secret within the party.
In his letter, Mr Brincat says there is no room for divisive and controversial figures, and refers to "eminent contenders for the leadership race" who have made it publicly clear all along that they felt, and would continue to feel, uncomfortable working with him.
During the leadership race Mr Micallef had also crossed swords with both former leadership contenders George Abela and Michael Falzon. Both have made it clear that they cannot work with the general secretary.
Mr Brincat's message to the delegates follows a series of such letters sent to different media by himself, leadership contender Evarist Bartolo and even former general secretary Jimmy Magro - all pushing the case for change.
Still, the frontrunners, according to Labour sources, appear to be Mr Micallef and Alfred Grixti, as was the case in 2003, even though predictions can be tricky this time given the large number of candidates running for the post.
There are six candidate, running for general secretary, including Joe Vella Bonnici, Gino Cauchi, Keith Grech and Joe Chetcuti.
Nonetheless, the system so far is that first past the post wins, which means the person who gains the most votes will become the next general secretary.
Labour sources said many felt this might favour Mr Micallef as the "opposing block" is fragmented.
An attempt to change the system to one where the winning candidate would need a majority was made last week, but the initiative was aborted after a number of delegates, who had signed the petition calling for this change, inexplicably pulled out.