The federal Liberals won’t change a decision that effectively halts an expansion of the island airport in downtown Toronto, with the new transport minister calling it a “quality of life issue” for the city’s residents.

Transport Minister Marc Garneau said Friday he intends to stick with a decision to reject a request from Porter Airlines to renegotiate an airport agreement among the City of Toronto, Ports Toronto and the federal government to extend the runway at Billy Bishop airport to allow jets to land.

The Liberals promised before and during the federal election not to open the three-party agreement.

Garneau said the promise was based on concerns from many voters in Toronto about what an airport expansion would mean for the future of the city’s waterfront.

The decision made earlier this month goes beyond concerns about noise from larger planes landing at the island airport, he said.

“It’s bigger than that,” Garneau said in a telephone interview. “It’s an issue that is an election promise and its main focus is on the fact that Torontonians want to have a greater say in the development of their waterfront.”

Critics have asked the Liberals to reconsider the decision, pointing to the fact that the city and Ports Toronto are releasing assessments and feasibility studies early next year. Garneau said there was nothing that would make him reverse course on the decision.

“Not with respect to opening the tripartite agreement,” he said. “Sometimes issues are quality of life issues and those are important.”

Garneau first announced the decision on Twitter on Nov. 12. Opponents of the expansion celebrated the move — the group NoJetsTO has a victory party planned for Monday — while the Ontario Progressive Conservatives, the Opposition in the provincial legislature, have said the decision will hurt the local, provincial and national economies.

Ontario Tory MPP Monte McNaughton told Garneau in a letter sent a week ago that the airport expansion could result in $250 million a year in economic benefits to Toronto, based on a City of Toronto study and potentially 2,000 jobs at Porter Airlines and Bombardier.

McNaughton said there is too much economic potential for the federal Liberals to shut the door outright on expanding the airport.

“This is an important project for the country, for the province and for Toronto. The economic case for this speaks for itself,” McNaughton said.

The decision could also be important to Bombardier and its CSeries plane.

In 2013, Porter placed an order worth US$870 million for a dozen of the 110- to 125-seat CSeries aircraft on the condition that they would be allowed to fly into the island airport. It also has options for 18 more aircraft that would raise the list price to US$2.15 billion if all options are exercised.

Montreal-based Bombardier has 603 purchase commitments, including 243 firm orders, for the plane, but hasn’t secured an order in more than a year. The plane itself is more than two years late and US$2 billion over budget.

The Quebec government has agreed to give Bombardier US$1 billion to help complete development of the CSeries in exchange for a 49.5 per cent stake in the project.

The province and company are now looking to the federal government for extra help.

– With files from Ross Marowits in Montreal