QUEBEC -- The NDP and Conservative plans to deal with the Senate were met with criticism Friday by the premiers of Quebec and Ontario.

Ontario's Kathleen Wynne said NDP Leader Thomas Mulcair's proposal to abolish the Senate is not realistic and can't be done without provincial support.

Wynne, who is actively campaigning for Liberal Leader Justin Trudeau, said Mulcair's proposition couldn't move forward without the support of provinces or without reopening the Constitution.

On Wednesday, Mulcair told the CBC an NDP victory next month would give him a mandate to talk to the provinces about abolishing the upper chamber.

"What I find interesting about the proposal is that it is unrealistic -- it is not rooted in what actually would have to happen," Wynne said. "There would have to be a process, there would have to be a national discussion, so it's not realistic."

Wynne said she was on the same page as Quebec Premier Philippe Couillard, with whom she shared a podium following a joint cabinet meeting in Quebec City.

Couillard said abolishing the Senate would not be in Quebec's interests and he repeated his take that it is a fundamental element of the Canadian federation that can't be changed without a constitutional discussion.

"It cannot be done without the provinces -- changing or abolishing, whatever you want to say -- and without a constitutional conference during which we will have other topics to discuss," Couillard said.

"The abolition of the upper chamber is totally contrary to Quebec's interests, and I will always object to that."

The Quebec premier also criticized the moratorium on nominating senators proposed by Conservative Leader Stephen Harper in July.

"What I read is that some leaders say they will not appoint senators anymore which is a way of doing indirectly what they can't do directly, which also I object to," Couillard said.

On Thursday, Bloc Quebecois Leader Gilles Duceppe said the NDP leader knows the Constitution won't be reopened just to discuss the abolition of the Senate.

The Constitution has a "double lock" on it and cracking it open to talk about the Senate is a non-starter without Quebec's demands as well as those of the First Nations on the table, Duceppe said Thursday.