Well-placed sources say referring the matter to the police is an option that has been considered in the past by members of the board of internal economy, the multi-party committee that oversees House of Commons spending.
And they say it's still a "live" option that could be employed if the NDP continues to thumb its nose at the board, which has ordered 68 MPs to personally repay a total of $2.75 million.
Multiple sources spoke to The Canadian Press on condition of anonymity because they were not authorized to speak for the ultra-secretive board.
The board ruled last August that New Democrat MPs improperly pooled money from their Commons office budgets to pay the salaries of 28 staffers working in satellite party offices in Montreal, Quebec City and Toronto.
In the days leading up to that decision, sources say draft motions for dealing with the matter were circulated to all board members. Several included referring the matter to the appropriate legal authorities.
However, the police option was shelved on the recommendation of Commons Speaker Andrew Scheer, who chairs the board. The sources say Scheer had been approached by the NDP about negotiating a settlement and he feared involving the police would poison any goodwill.
New Democrats have insisted all along that they did nothing wrong, that the satellite office employees worked strictly on parliamentary matters for MPs. They've dismissed the board as a partisan "kangaroo court" and applied to the Federal Court to overturn the board's ruling.
The court challenge was suspended in November while the two sides attempted to reach an out-of-court settlement. But earlier this month, when the board began issuing bills to the 68 MPs for their share of the scheme, NDP House leader Peter Julian declared that the party would revive the court case.
Some three weeks later, the court case remains suspended, fuelling suspicions among rival parties that the NDP is simply trying to rag the puck until after the next federal election, scheduled for October.
The board has given the New Democrat MPs 90 days — until early May — to reimburse the Commons or face having their salaries or other sources of Commons funding garnisheed.
If there's no movement by then, the sources predict the option of referring the matter to the police will be back on the table.
Asked about that possibility, a spokeswoman for government whip John Duncan, who sits on the board, said: "The minister cannot comment on the matter until the board makes a decision and authorizes him to do so."
Scheer's office declined to comment.
However, a report earlier this month from House of Commons administration to the board, noted that going to the police is still an option.
"Where, in the opinion of the board, an expenditure or use of funds, goods, services or premises may constitute an offence under any applicable federal or provincial law, the board may refer the matter to the competent authority," says the report, shown to The Canadian Press.
Karl Belanger, a spokesman for NDP Leader Tom Mulcair, scoffed at the potential threat.
"We've been wanting to bring this matter in front of a real court for quite some time so this partisan kangaroo court can bring it on," Belanger said.
"We have nothing to hide, contrary to our Liberal and Conservative opponents hiding behind closed doors and smearing anonymously."
However, rival parties say there's little difference between what the NDP MPs are accused of doing to unlock Commons funds to pay for the satellite office workers and the schemes undertaken by other parliamentarians who've run afoul of the law for making false expense claims.
The MPs were required to fill out employment forms which asked them to tick one of two boxes indicating that the employee worked either in the MP's Ottawa office or the MP's constituency office. In the case of the satellite office workers, one of the two boxes was checked, even though neither applied.
Senators are required to fill out similar paperwork when applying for housing allowances. Disgraced senators Mike Duffy, Patrick Brazeau and Mac Harb have all been charged with allegedly making false claims about the location of their primary residences in order to claim such funds.