Alberta Premier Danielle Smith says the Alberta NDP don’t have “any credibility” on affordability until party leader Rachel Notley denounces the federal government’s carbon tax increase.

At its convention in Calgary over the weekend, NDP delegates passed a resolution seeking to address high costs at grocery stores by calling on the United Conservative Party (UCP) government to work directly with the Opposition to create an all-party committee on food affordability.

But Notley supported federal NDP leader Jagmeet Singh who voted with the Trudeau Liberals to increase the federal carbon tax, Smith said outside the Government House in Edmonton on Monday.

“Quite frankly, I don’t think that any of (Notley’s) statements on (affordability) have any credibility until she’s prepared to argue against that,” Smith told True North.

“I welcome Rachel Notley saying that she rejects a 300% increase in the carbon tax. That’s the number one thing that she could do. Because if she wants to bring affordability to the fore, then she can’t be adding arbitrary costs on gasoline, diesel, electricity, home heating.”

Amid record fuel prices across the country, the carbon tax increased in April to 11 cents per litre of gasoline, 13 cents per litre of diesel and 10 cents per cubic metre of natural gas.

Smith, who was sworn in as premier last week after winning the UCP leadership race earlier this month, also took aim at the carbon tax increase during her speech to party members at the UCP annual general meeting over the weekend. She said the “NDP-Liberal coalition” increased the carbon tax by 300%, costing Albertan families almost $1,000 per year after rebates.

The federal NDP has agreed to keep the Liberals in power until 2025 in return for progress on NDP policies like a national dental care program.

“Have these folks lost their minds,” Smith said on Saturday. “Yes, they have.”

The UCP government suspended the 13 cent-per-litre provincial fuel tax on April 1 to help Albertans with the cost of living crisis. Once oil prices fell, the government added a tax of 4.5 cents per litre on gas and diesel on Oct. 1, which will continue until the government re-evaluates fuel costs at the next quarter.

Following the swearing-in of her new cabinet on Monday, the premier also told True North she will make ministerial mandate letters public once they’re ready. Mandate letters outline ministerial priorities.

“I think it’s a good communication tool for the public, so that the public knows what it is that we’re working on,” she said.

“And why wouldn’t we want to tell, we’ve had such great success in checking off the list of all of the things that had been identified so I think that we should be celebrating that.”