With one poll suggesting the Liberals have surged in support amid voter concern about sovereignty and a possible referendum, the PQ has been moving to switch the election focus in recent days.
The cabinet minister who served as the principal architect of the charter said only a PQ majority on April 7 can ensure it will become law.
"If Quebecers want to have a charter of values, they have to vote for the Parti Quebecois because we are the only party supporting the charter," Bernard Drainville told a news conference.
"All other parties oppose the charter in some shape or form."
Before PQ Leader Pauline Marois called the election on March 5, the charter was expected to be a major issue during any campaign after dominating public debate in recent months.
Instead, the proposed legislation has been overshadowed by economic concerns and the threat of another independence referendum.
On Wednesday, Drainville denied he was talking about the charter because of poll results. He said it was always his intention to discuss it about two weeks into the campaign after visiting 15 key ridings in recent weeks.
None of the targeted ridings was in Montreal, where support for the charter is weak compared with outlying regions.
The party released an advertisement with Drainville on Wednesday with a message: "A vote for the PQ is a vote for the charter."
The proposed charter would restrict government employees from wearing religious symbols or clothing on the job.
Marois has also suggested during the campaign that private enterprise would be free to adopt its own directives inspired by the charter.
While popular with many Quebecers, the proposed legislation has also been fiercely opposed and has prompted large demonstrations.
One such anti-charter protest is planned for Friday evening in Montreal.
Marois was mainly absent from the campaign trail on Wednesday as she prepared for Thursday's televised debate with the leaders of the three other main parties.
Liberal Leader Philippe Couillard was also discussing the charter Wednesday as he accused the PQ of using the topic as a diversion from referendum talk.
"They used the charter in the fall to deflect attention from the economic failure," Couillard said in Quebec City.
"Now they will use the charter of values, or the so-called charter of values, to deflect attention away from the referendum."
Asked if the PQ would be willing to put sovereignty on the backburner to firm up charter support among voters, Drainville said the two topics were unrelated.
"You're trying to make a linkage where there is no linkage to be made," he said.
Drainville renewed a promise to look at "improving" the charter, but did not explain how.
As it stands, the plan would affect every public servant. That includes judges, police, and prosecutors; public daycare workers; teachers and school employees; hospital workers; and municipal employees.
The ban would apply to hijabs, kippas, turbans and large crucifixes.
"If you wear a niqab and you wear a burka and you work for a public institution, if the charter is adopted, it will be no longer possible for you to wear a niqab and the burka," Drainville said.
"And if you want to ask for a service of the state, you'll have to withdraw your niqab or your burka because the rule of an unveiled face will be ... implemented through the charter."
Drainville was particularly critical of Couillard, accusing him of having a position on religious symbols that is weaker than the party's under Jean Charest.
The Charest Liberals, in 2010, had planned to ban the wearing of niqabs and burkas for those hoping to receive public services.
For his part, Couillard said he has a very simple question for Drainville, one he predicted the PQ candidate wouldn't answer.
"How many nurses will be fired, how many doctors will not be allowed to treat patients, how many daycare workers will be forbidden to be with children?," Couillard asked.
"Is that the way they envisage relations in Quebec? I want to create jobs, not destroy jobs."
Drainville was surrounded by other pro-charter PQ candidates, including one who said the "silent majority" supports the legislation but is intimidated by its opponents.
PQ candidate Yasmina Chouakri said she has met people who support the charter but won't openly admit it for fear of being accused of xenophobia or Islamophobia.
"They compare the charter to Putin, Franco, Le Pen .... so it's understandable that people, seeing this anti-charter hype by some commentators, end by saying 'My God, should I support the charter? Am I a good person?'," Drainville said.
"(We say) of course, you are a good person madame, sir, you are part of the majority who want a charter."
One absentee at the news conference was PQ candidate Louise Mailloux, who came under intense scrutiny last week for previous remarks that some people deemed anti-Semitic.
She issued an apology over the weekend to anyone who was offended by her comments, which included saying kosher-food premiums amount to a "tax" that ends up funding religious extremism. She has also equated baptism and circumcision to rape.
It isn't clear if Maiiloux still harbours the same views. She has not granted interviews and the party has resisted calls to condemn her statements.
For Drainville, the Mailloux matter is closed.
"She made personal remarks before being a candidate for the Parti Quebecois, she has since apologized for these remarks and she fully adheres to the charter as we have proposed it," Drainville said.
"As far as we're concerned, that's the end of it."
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