Joe Vella Bonnici has made huge gains in a tight race for Labour general secretary over the past week after senior Labour figures made a concerted effort to prevent Jason Micallef's re-election.
Former deputy leader Michael Falzon is the latest heavyweight to publicly urge delegates not to vote for Mr Micallef - he sent a seven-page e-mail heavily criticising the general secretary in recent days - following respected MP Leo Brincat's scathing letter to The Sunday Times last week.
Party sources said that despite being a relatively unknown figure within the party, Mr Vella Bonnici gained most from the surprise withdrawal of Gino Cauchi and Joe Chetcuti last Thursday. However, the other major contender, Alfred Grixti, has also gained ground.
Mr Micallef was ahead for several weeks, benefitting from the fact that the bloc against him was split among five candidates. With the current first-past-the-post system, he could have been elected with little more than 20 per cent of the vote.
The only other candidate, Keith Grech, has hardly featured in straw internal polls being conducted by the party's different factions.
"Besides the fact that Keith (Grech) is behind, I would not dare make a prediction it's so tight," a Labour source said. "What's sure is that Mr Vella Bonnici made massive gains in the past week and this could propel him to victory".
However, Mr Grixti is also a potentially strong candidate. Sources said: "He has been running a very strong and steadfast campaign with the grassroots for months and that has to be taken into account."
Labour sources said the upheaval was partly triggered by the letter written by Mr Brincat - a highly respected figure within the party - who urged delegates in no uncertain terms to oust Mr Micallef.
"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," he wrote referring to Mr Micallef.
"This is the kind of arrogance that I hope delegates will push aside," he continued.
Only a few days later, Dr Falzon replied to an e-mail - sent by a supporter of Mr Micallef to delegates - with a blunt seven-page response, in which he drew up an interminable list of reasons why he will not be voting for the incumbent.
Referring to the man who sent the original letter as an old friend and a genuine Labourite, Dr Falzon in his reply nonetheless reiterated the criticism he had levelled at Mr Micallef shortly after the leadership contest, and was even more scathing in places.
"I am not going to vote for someone who regularly has around him people with a shameful past," he says in an indirect reference to Ronnie Pellegrini, a former assistant to the disgraced Labour minister Lorry Sant who has assisted Mr Micallef's campaign.
"I'm not going to vote for someone who at 11 p.m. on March 9 made an irresponsible statement on One TV, saying that the result (of our vote counts) was not tallying with that of the Nationalist Party when the result had been known for hours, even by him," he continues.
When contacted, Dr Falzon would not be drawn into elaborating on certain other parts of the letter, saying that the e-mail was not intended for public consumption.
However, he confirmed that the letter was his and that he had copied it to the delegates who received the original e-mail.