Marois and her spouse, Claude Blanchet, have been called to testify before a committee once the legislature resumes sitting March 11.
The controversy revolves around a 2009 wiretap that was played recently at the provincial corruption inquiry that hints at an arrangement between Blanchet and the Quebec Federation of Labour.
An Opposition motion calling for Marois and Blanchet to appear before a committee was passed Thursday, but an election will likely be called before mid-March, meaning the couple won't need to testify.
The recording captures Michel Arsenault, who was then president of the labour federation, saying he was ready to enlist the aid of the Parti Quebecois to help thwart a corruption probe and that the labour union has a "deal with Blanchet."
"The PQ won't touch this," Arsenault is heard telling another union boss. "I'll talk to Pauline."
Marois was in opposition at the time of the recording.
Arsenault later explained it as "brainstorming" and said it was a mistake to say it.
But the recording raised questions about the type of influence the union wielded with the Parti Quebecois, which was elected with a minority government in 2012.
Despite the couple insisting they did nothing wrong, the opposition parties have said they're not satisfied with their responses.
"We want the truth, and I think the Quebecers need (an) explanation," Liberal ethics critic Lise Theriault said Friday.
Theriault said premiers who have been asked to testify at legislature committees in the past have done so.
Blanchet recently issued a statement to denounce "misleading statements" from elected officials that were "false, malicious and defamatory and unacceptable." He added he has never, directly or indirectly, tried to influence anyone.
A lawyer for the Parti Quebecois also dealt with the matter at the Charbonneau Commission, questioning Arsenault about it at length in cross-examination.
But the opposition parties say plenty of questions need answers.
In particular, they have questioned how the labour federation's Solidarity Fund made an investment of just under $3 million in 2008 in BLF Capital, a company partly controlled by Blanchet, when the firm had nothing to do with the fund's mandate.
They also want to know why the fund paid for shares at a price three times that which Blanchet had paid himself.
Marois and Blanchet have both said there was nothing questionable about the business transaction and that there was no deal with the labour federation.
Blanchet is a successful Quebec businessman who served as head of the fund from its inception in 1983 until 1997. He is no longer involved in BLF Capital.
If not addressed at the committee, the issue could surface during the election campaign. The Coalition for Quebec's Future, which has repeatedly asked questions in the legislature about the subject, said it wants full answers before then.
"It is inconceivable that elections can be triggered without getting to the bottom of this story," said Coalition finance critic Stephane Le Bouyonnec.