Denis Coderre is fending off criticism over a decision by Montreal-area mayors to oppose the Energy East pipeline project, with political leaders from both sides of the country saying the city should put national interests ahead of local concerns.

The Montreal Metropolitan Community, a grouping of 82 Montreal-area municipalities that's led by the Montreal mayor, came out Thursday against the Energy East plan.

​The group's opposition is the latest challenge to TransCanada's proposed project, which would carry 1.1 million barrels a day of oilsands crude through Quebec to an export terminal in Saint John, N.B.

Coderre said the decision was based in part on the findings of public consultations held by the MMC last fall that heard extensive concerns about possible environmental impacts of the project.

The announcement sparked a torrent of criticism from western Canada, including rebukes from federal Conservative Party interim leader Rona Ambrose, Calgary Mayor Naheed Nenshi​, Alberta's finance minister Joe Ceci and Saskatchewan Premier Brad Wall.

"I trust Montreal area mayors will politely return their share of $10B in equalization supported by west," Wall wrote on Twitter.

Coderre fired back at Wall on Friday, tweeting in French that the Montreal Metropolitan Community represents four million people while the entire province of Saskatchewan has a population of 1.13 million.

Coderre also tweeted that Quebec taxpayers support Saskatchewan through federal grants.

Wildrose versus Coderre

Coderre also took to the airwaves in Alberta Thursday to take on comments by Brian Jean, leader of the provincial Wildrose Party.

Jean issued a statement Thursday that called Montreal's opposition to Energy East on environmental grounds "hypocritical" given the city's decision to dump eight billion litres of untreated sewage into the St. Lawrence River last fall.

Coderre said the comparison doesn't work.

"[Wastewater] dumps happen everywhere in Canada," he said.

"An oil spill can't just be turned off, and it would affect multiple waterways, including water basins and groundwater — you have to take all of this into consideration."

Coderre also pointed to the fact it's not just Montreal that's opposing Energy East, but communities in Ontario and First Nations communities in both Ontario and Quebec.

'We have to be working together'

On Friday, New Brunswick Premier Brian Gallant added his voice to the chorus questioning Coderre and the MMC.

Speaking from the World Economic Forum in Davos, Switzerland, Gallant said Energy East is important for his province, where the pipeline would feed an oil export terminal in Saint John.

"We have to be focused on creating jobs and growing the economy," he said.

"We have to be working together… This is a project that could help us stimulate the economy, create jobs and help ensure that there's long-term economic growth."

That sentiment was echoed by Yves-Thomas Dorval, President of the Quebec Employers Council.

Dorval told CBC Montreal's Daybreak Friday that Montreal should be cooperating with the rest of Canada to create "the best economic environment for the country."

"We support the business and economic case for the pipeline," he said. 

Dorval acknowledged, however, that environmental concerns about the Energy East project remain that TransCanada needs to address.

In that sense, Dorval said the MMC's decision was "legitimate."

"They did what they had to do. It was a consultation and there are real risks that have to be evaluated," he said.