This week's first ministers meeting in Vancouver will be a tough reality check for the Liberal government's ability to make good on one of its most high-profile election promises — tackling climate change.

Prime Minister Justin Trudeau is in Vancouver this week ahead of the talks, helping to kick off a green economy initiative called Smart Prosperity.

Sources have told CBC News that the preparations with the provinces and territories have been testy. Officials have been parsing every word toward the final declaration that will include a working group to look at options for a pan-Canadian approach to pricing carbon.

The mere mention of a carbon price is expected to suck up a lot of the oxygen in the one-day closed-door gathering, with Saskatchewan Premier Brad Wall emerging Monday as the head of the No side against any tax on carbon.

"The timing for this is simply not now," Wall said. "And if there is a national carbon tax that is a part of these agreements or declaration … to be signed in Vancouver this week, I will not be signing them."

Wall, who is facing an election in April, told reporters that the federal government is floating the idea of a $15 a tonne carbon tax that could increase to $40 a tonne.

Saskatchewan Premier Brad Wall says he will not sign any declaration that includes putting a price on carbon. (Adrian Wyld/Canadian Press)

"I can tell you that with the energy sector reeling in Canada, with the overall Canadian government struggling, it's my view, it's the Saskatchewan government's view, that the very last thing we need right now is another new tax," Wall said.

In a Tuesday news conference, Trudeau hearkened back to the presence of several premiers at the COP 21 environmental meetings in Paris late last year, where Canada agreed to a deal that would try and keep global warming "well below 2 degrees C."

"Canada needs to step up in its fight against climate change and not to look at it as simply an obligation that we've signed on to that we're going to have to figure out how, but understand the tremendous opportunity that comes with being innovative and responsible around pricing pollution, around ensuring a level playing field and ensuring the kind of leadership that, quite frankly, Canadians and citizens of the world are expecting from Canadians," he said.

A senior federal official who spoke to CBC on background said the bottom line on carbon pricing is with the premiers, and Prime Minister Trudeau must come away from their Thursday gathering with an agreement on the next step to move forward on the touchy issue.

"We need to have a broad agreement on a national carbon price," said the source. "We need to get the chain on the bike."

The official said his government is "not looking to have a fight" with Wall. But the source also pointed out the position the premier has been taking is one few big petroleum companies agree with.

"The majors all want a price on carbon," said the federal official. "They want a policy that will get their goods to market."

Smart Prosperity coalition

Today a new group of 26 influential Canadians is launching an effort to help provide some momentum toward an agreement.

Smart Prosperity is a coalition that includes leading businesses like Canada's largest retailer Loblaws, Shell Canada and the Royal Bank, as well as clean tech groups, aboriginal and environmental organizations.

It's launching today to make the case for swift action toward a cleaner economy by leading through example and urging others to do the same.

That action includes putting a price on pollution.

"We very much want to blow wind into the sails of the prime minister and provincial leaders who are coming together at a historic time to try to deal with both climate change, but also building a cleaner economy for Canada," said Stewart Elgie, who is an economics and law professor at the University of Ottawa and co-chair of Smart Prosperity.

Trudeau said the initiative is a sign that economic development doesn't have to be at odds with environmental concerns.

"We all know that in the new global context, sustainability is sound business strategy. We all know that investing in innovation, supporting clean technology and encouraging sustainable practices will foster emerging industries, job growth, market access and global competitiveness," he said.

"In short, new growth will be clean growth."

Working groups

The prime minister and premiers are expected to emerge Thursday with agreement to set up four working groups to consult and study the following areas:

Clean technology and innovation.

Mitigating climate change (reducing emissions).

Adaptation.

Pan-Canadian price on carbon.

Their work will take six months and the groups will report back to the first ministers in the fall.

Ultimately, said the senior federal official, it's about keeping up the political momentum created in December when many of the premiers and some mayors joined Trudeau in Paris for the climate summit.

"Let's not forget that smiling picture of all of the premiers and mayors who were saying, 'Yes, we want to do this.'"