As recently as Sunday, Singh vehemently denied he's working in concert with Mulcair.
Yet Singh's former western organizer, Sukh Johal, confirmed Monday that he's now working for Mulcair.
Johal told The Canadian Press he signed up 4,500 members from British Columbia's South Asian community for Singh. He ceased working for Singh on Feb. 18, the deadline for signing up new party members eligible to vote in the leadership contest.
Now, Johal said he's volunteering for Mulcair, urging the same people he recruited for Singh to mark Mulcair as their second choice on their preferential ballots.
What's more, he said he suspects Singh might openly deliver the same message to all his supporters in the next day or two.
However, Singh campaign manager Wally Steven called Johal's assertions "a work of fiction."
"Sukh Johal is a disgruntled, ex-member of our campaign who was let go for non-performance and non-compliance," Steven said in a email.
"Anything he says is suspect. He has nothing to do with our GOTV (get out the vote) effort and we have not included these unsubstantiated (membership) numbers in our calculations."
Johal's picture remains on Singh's website, in a photograph with Singh and Manitoba Premier Greg Selinger, although his name appears to have been removed from the caption.
For his part, Johal said he personally still intends to rank Singh as his first choice, with Mulcair as his second choice. While he stressed he no longer speaks for the Singh campaign, Johal repeatedly referred to "we" and "our" when talking about Singh's team.
"We had a strong membership drive. We signed up about 4,500 members here locally .... So the membership drive is over now and I'm assisting with Tom," Johal said in a telephone interview.
"I'll be communicating to the membership that we did sign up that Tom will be our second choice."
With the vast majority of New Democrats expected to vote online or by mail before the March 24 convention, it would be important for Singh to signal his second-choice preference soon if he wants to influence his supporters.
Under the preferential balloting system used by the NDP, voters may rank their choices first through seventh. When a voter's first choice is eliminated, their second choice is counted.
Johal said he expects Singh will stay in the race until he's forced off the ballot at the convention but said he might tip his hand within the next day or two.
"Martin's in it right to the end ... but I think you might hear something from him in the next couple of days possibly."
Asked if he expects Singh to urge all his supporters to rank Mulcair second, Johal said: "I can't give you a concrete answer on that but it's a possibility, right?"
He added it's "a firm possibility" that Singh will wind up being the king-maker in the close-fought contest.
"He's in it to win and he's done extremely well through this membership race but, at the same time, we want to make sure we take the right steps towards the end of the campaign."
Johal said it's important to ensure Mulcair emerges victorious.
"Out of the seven candidates, I think Tom is the guy that has the ability to, you know, take on Stephen Harper and the Conservatives and eventually form government, right? So if you want to form government, we've got to make sure we have someone who's got the experience, charisma and presence to defeat Mr. Harper and I think Tom brings that to the table."
The Mulcair camp did not respond to requests for comment on Johal's revelations. Both the Mulcair and Singh teams have previously denied employing a co-ordinated strategy in which Mulcair sticks to a resolutely positive campaign while Singh goes on the attack against the front-runner's top rivals — a perception shared by all other rival camps.
Jim Rutkowski, a spokesman for rival contender Brian Topp, who's been the target of the fiercest Singh attacks, said it now appears "the story is changing."
"Yesterday, Mr. Singh assured voters he wasn't working for anyone else in the campaign."
During Sunday's final leadership debate in Vancouver, Singh angrily denied accusations that he'd played the role of Mulcair's attack dog during previous debates.
B.C. MP Nathan Cullen asked Singh if he wanted to apologize for accusing Topp of lying about his tax proposals, wanting to limit abortion rights and even of suggesting Jack Layton, the NDP's late revered leader, wasn't a good New Democrat.
Singh refused, repeating his assertion that Topp "did not tell the truth" about his tax policy.
"Moreover, I will not be bullied into backing down from the truth because of false accusations about me co-ordinating debates with other candidates," Singh added. "Make no mistake, I'm in this to win and my debate strategies are my own."
Cullen did not follow up, telling reporters later he finds Singh's accusations against Topp to be "outrageous and offensive" and he didn't want to give him any more air time.
Also on HuffPost