In a statement on Wednesday, the party said the rule would only apply to newcomers to the province. They would be obliged to take a test in order to receive Quebec citizenship.
The PQ said its policy would not actually force people who currently live in the province, including aboriginal people, to prove that they speak French to run for municipal or provincial office.
Ghislain Picard, an Assembly Chief of First Nations in Quebec and Labrador, said "none of the First Nations in Quebec [will bend to] a foreign law adopted by a provincial government."
Liberal Leader Jean Charest said "in the case of the PQ, it's just a demonstration of improvising about an issue, that frankly, isn't an ordinary issue."
The Liberal Party had introduced a waiver that immigrants to the province would sign, stating that they recognize traditional Quebec values.
Charest also mentioned that Coalition Avenir Québec Leader François Legault, a former member of the PQ, used to be a staunch supporter of the party's citizenship plan.
On Tuesday, the PQ leader said anglophones, allophones and aboriginal people would be forbidden from seeking municipal or provincial office under the policy unless they have an appropriate knowledge of French but failed to clarify.
Marois said the idea is reasonable, given that French is the official language of Quebec.
"We will present this bill but it is not just for new Quebecers — it is for everyone," said Marois. "All Quebec citizens who want to be elected as a mayor or a councillor, as a member of the legislature, must have a knowledge of French."
Without that ability, a person could not be a candidate in elections, participate in the public financing of political parties or petition the legislature to address grievances.
'Common language here is French'
"In the case of anglophones, be it a native or a new arrival, listen, the common language here is French," Marois said. "Is there anyone who can imagine not knowing it?"
Marois has said during the campaign for the Sept. 4 provincial election that she would toughen Quebec's language laws if the PQ takes power, and introduce a Quebec citizenship.
The latest language proposal could potentially have its greatest impact in aboriginal communities.
Kitty Gordon, a spokeswoman for Makivik Corp., which oversees resource development in Quebec's north, expressed outrage at the PQ plan.
"I think it's kind of ridiculous for anglophones and aboriginals," she said in a telephone interview.
"Are they saying that the Quebecers were here first so that's why we have to speak French? It's like saying the Inuit were here first so you all have to speak Inuktitut."