MONTREAL -- Integrity resurfaced as a Quebec election issue Monday with party leaders each trying to position themselves as the best to follow through once the Charbonneau Commission tables its final report next year.

The Philippe Couillard-led Liberals lack credibility and have too many links to former leader Jean Charest, the Parti Quebecois's Pauline Marois said.

"They have done things in the past that are worrisome," said the PQ leader who stopped short of calling the Liberals corrupt.

Marois highlighted the Liberals' steadfast opposition to holding a corruption inquiry before Charest finally relented under intense pressure in November 2011 and formed the Charbonneau Commission.

Liberal candidate Michel Matte said Sunday some members expressed the desire behind closed doors that an inquiry be held more quickly. Matte held the riding of Portneuf from 2008 to 2012.

Marois repeated that 18 incumbent Liberal candidates repeatedly rejected a corruption inquiry on numerous occasions in the national assembly. Marois said such behaviour suggests they lack credibility to follow through on the Charbonneau Commission's recommendations.

The commission is scheduled to issue a final report in April 2015 and Marois says the battle against corruption is far from over.

Given Matte's comments, Marois also called on those incumbent Liberals to provide explanations.

"They should have the courage to say whether they were for or against a commission of inquiry," Marois said.

Marois also promised her party would introduce whistleblower legislation if elected on April 7.

In Trois-Rivieres, Coalition Leader Francois Legault also pounded the Liberals for their record under Charest and said if voters want real change, they should opt for his party.

As the Liberals have risen in the polls, the attacks against Couillard have increased and Charest's name has come up more frequently.

In Charest's old riding in Sherbrooke, Couillard repeated his own wish that the inquiry had been called more quickly. But the Liberal leader also suggested the delays haven't had an impact on the inquiry's work.

"I think that it would have been beneficial to have it earlier," Couillard said. "That said, the inquiry is in place and its benefits will be the same. The delay will not make it less useful. To the contrary, it may make it even more useful."

Couillard said he's eager to see the final report from Charbonneau.

Attending a business speech by Charest on Monday, former Liberal finance minister Raymond Bachand brushed off Marois's allegations.

"Is there an inquiry?" asked Bachand. "There is."

Bachand, who has retired from politics, noted the Liberals also previously introduced the permanent anti-corruption unit, known as UPAC, as well as the provincial police Hammer squad to investigate the construction industry.

"That's the order in which things should be done," Bachand said. "No inquiry is good if you don't have police inquiries preceding it."

Charest, who has been largely quiet during the election campaign, slipped out after his speech without talking to reporters.

Couillard said he didn't expect Charest to intervene in the election campaign. One of Charest's former advisers, Luc Fortin, is attempting to win back Sherbrooke from the PQ.

"He plays a role that's very discreet compared to his PQ predecessors who we see often on the trails and he doesn't get involved in the campaign at all," Couillard said.

The reporters attending Charest's speech included some of those following Couillard's campaign. They happened to be staying at the Montreal hotel on Monday night.

- with files from Patrice Bergeron in Trois-Rivieres and Alexandre Robillard in Sherbrooke.