Evidence at the Charbonneau Commission, which is looking into the construction industry, suggested the Quebec Federation of Labour was ready to lobby Marois and the Parti Quebecois in 2009 to put a stop to any future corruption probe.
Marois said no such intervention took place and that she was never pressured by the federation's directors.
"No agreement was reached, there was no deal, as they say," Marois said with a laugh during a press briefing in Davos, Switzerland, where she was attending the World Economic Summit.
In a wiretap played Tuesday at the Charbonneau inquiry in Montreal, two union executives were overheard talking in 2009 about applying pressure to the PQ to ensure no such inquiry took place.
Then-union president Michel Arsenault reassures Jean Lavallee that they have a deal with "Blanchet," a reference to Marois' husband, Claude Blanchet, a director at the labour federation's Solidarity Fund from 1983 to 1997.
"The PQ won't touch this," Arsenault tells Lavallee, ex-president of the labour federation's construction wing. "I'll talk to Pauline."
Marois was leader of the Opposition in 2009.
The first-name reference prompted the Opposition Liberals and the Coalition for Quebec's Future to express concerns about the type of influence the union may have had on Marois.
Her comments did little to appease those parties Wednesday.
"I'll have to take her word for it, but her husband could perhaps explain what this 'deal' was," said Sylvie Roy, a Coalition member of the legislature.
Roy was the first to call for a public inquiry and, given the wiretap, the Coalition has asked why it took the PQ six months to come on board in support of a full public inquiry.
Treasury Board President Stephane Bedard responded that Marois' answers were clear. Bedard wouldn't go into much detail about the so-called Blanchet deal, except to say there wasn't one.
Earlier in Europe, the premier downplayed the influence the labour federation has on the party.
"You might have noticed that while the QFL had usually supported the Parti Quebecois, that wasn't the case in the last two elections," Marois said.
Marois said union brass were informed quickly that her party intended to push for a public inquiry and added the relationship her husband had with the union was strictly business.
They didn't agree on the necessity of one, but Marois insisted Arsenault did not pressure her.
"I decided that we would ask for a commission of inquiry regardless of what any group thought, be it the QFL or anyone else. If they spoke to us, and they speak to us regularly, it didn't yield the desired results."
The Liberals, in power at the time, finally agreed to call an inquiry in November 2011.
Meanwhile, at the commission on Wednesday, lawyers continued to study the close ties between Lavallee and former construction magnate Tony Accurso.
Lavallee admitted vacationing with Accurso as many as 20 times and never paying for anything.
"He was a guy with a big heart," Lavallee said of Accurso, a friend of more than 30 years. "With him, you weren't allowed to pay."
The commission entered into evidence scores of pictures of Lavallee vacationing in sunny locales with Accurso and even some from a trip to a weight-loss facility in Germany.
Lavallee said he had no issue with the trips he took.
"It doesn't bother me, as I've told you: he was like a brother to me," Lavallee testified. "And I was part of his family. He was more than just a friend."
Also on Wednesday, a PQ cabinet minister's name resurfaced at the inquiry.
In another wiretap, Elaine Zakaib, a former Solidarity Fund executive who is now responsible for industrial policy, is heard telling Arsenault she knew that certain files were blocked at the fund because they involved competitors of Accurso's.
Arsenault advises her to keep quiet and she agrees.
The April 2009 conversation came after an expense account scandal rocked the union brass. On that subject, Zakaib is cautious.
"The less I know, the better I feel," Zakaib is heard saying.
Wednesday's revelations led to an immediate Liberal call for her dismissal.
Former labour minister Lise Theriault says the fact Zakaib is now in charge of a dossier that involves public funds means it's time for her to step aside.
"She closed her eyes to a system of collusion," Theriault said.
Zakaib, meanwhile, defended her actions.
"I acted with integrity on this occasion and throughout my tenure as the head of the regional fund," she said in a statement. "My priority has been, and remains, economic development in the regions."
Zakaib won her first provincial election in 2012 after spending two decades at the fund manager in a variety of roles. Her name also came up last October as the inquiry listened to Quebec Federation of Labour-related wiretaps.
— With files from Sidhartha Banerjee in Montreal
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