Prime Minister Justin Trudeau says he doesn't understand why the federal New Democrats are pulling back their support for the carbon price, though he acknowledges they are facing political headwinds.

New Democrats have long been supporters of the climate policy, and even campaigned on it in the 2019 election.

But this week, the NDP shifted its position, saying carbon pricing is not the "be-all, end-all" and encouraging premiers to come up with new ideas to reduce greenhouse-gas emissions.

The NDP also backed a non-binding Conservative motion demanding that Trudeau sit down with provincial and territorial leaders within five weeks to discuss the policy.

The Conservatives insist that the carbon price is making life less affordable for Canadians, while the Liberals say rebates mean most Canadians end up with more money at the end of the day.

Trudeau says the Conservative message seems to be resonating with NDP Leader Jagmeet Singh, but the Tories say Singh is trying to run away from his record.

The Tories have introduced more than 20 motions in the House under leader Pierre Poilievre to scrap the federal carbon price.

The NDP voted against all but two of them.