Justin Trudeau's Liberal government is abandoning a commitment to reform the federal electoral system.

A new mandate letter issued to Minister of Democratic Institutions Karina Gould, released publicly on Wednesday, says "changing the electoral system will not be in your mandate."

Opposition MPs blasted the Liberal government's move as a cynical betrayal.

​"There has been tremendous work by the House of Commons Special Committee on Electoral Reform, outreach by Members of Parliament by all parties, and engagement of 360,000 individuals in Canada through mydemocracy.ca," Trudeau writes in his letter to Gould.

"A clear preference for a new electoral system, let alone a consensus, has not emerged. Furthermore, without a clear preference or a clear question, a referendum would not be in Canada's interest. Changing the electoral system will not be in your mandate."

Gould was appointed minister last month, replacing Maryam Monsef.

"Our view has always been clear. Major reforms to the electoral system, changes of this magnitude should not be made if they lack the broad support of Canadians," Gould told reporters at a news conference convened to comment on her new mandate letter.

"It has become evident that the broad support needed among Canadians for a change of this magnitude does not exist."

Minister of Democratic Institutions Karina Gould explains why the Liberal government is not moving forward with electoral reform. 8:06

Trudeau first committed to replacing the current first-past-the-post electoral system in June 2015, shortly before the federal election campaign. His government's first throne speech promised that the Liberals would "take action to ensure that 2015 will be the last federal election conducted under the first-past-the-post voting system."

A special committee of the House of Commons was struck last June and all MPs were invited to hold town hall meetings on electoral reform. In addition, Monsef conducted her own national tour and launched an online survey about the Canadian political system.

When the committee returned its final report to the House in December, a majority of members recommended calling a referendum on some form of proportional representation.

[Trudeau] certainly had no problems making the promise, but not the courage to break that promise in front of all of you here today. - NDP critic Nathan Cullen

"The past year was an incredible important conversation that we had with Canadians," Gould said. "We took the time, we consulted and we listened. And now we're moving forward with a plan that respects all of those contributions. I thank everybody who participated.

"It is a difficult conversation to talk about how we govern ourselves. But we have listened to Canadians and this will not be part of my mandate."

Cullen: 'One of the most cynical displays of self-serving politics'

Speaking to reporters after Gould, NDP democratic reform critic Nathan Cullen took direct aim at the prime minister.

"I was a bit surprised that it wasn't Mr. Trudeau out here, somehow lacking the courage and fortitude to make this announcement himself," Cullen said. "He certainly had no problems making the promise, but not the courage to break that promise in front of all of you here today."

NDP MP Nathan Cullen lambastes PM Justin Trudeau for breaking his promise to reform Canada's electoral system. 2:39

Cullen called it "one of the most cynical displays of self-serving politics this government has yet to engage in."

"What Trudeau proved himself today was to be a liar, was to be of the most cynical variety of politician," the New Democrat said. "Saying whatever it takes to get elected, then once elected seeking any excuse, however weak, however absent, to justify that lie to Canadians."

The NDP MP predicted Trudeau would pay a "political price" for abandoning his promise.

'Betrayal' will strike deeply, says May

Interim Conservative Leader Rona Ambrose told reporters outside the House of Commons that "Canadians should think twice about believing what Justin Trudeau says."

Green Party Leader Elizabeth May, a member of the special committee, warned that Trudeau's decision to walk away from his commitment could have significant ramifications.

"I am deeply afraid that this betrayal will strike much more deeply in the hearts of Canadians than Prime Minister Trudeau realizes, particularly among young people," she said before making reference to politicians who have led populist revolts in other countries.

"We are in a time of dangerous politics. You must never do anything as a politician who understands what's at stake that feeds cynicism. Cynicism has enough to feed itself. It is work to feed hope. It is work to feed faith. And when you break faith you will reap what you sow."

MPs Scott Reid and Nathan Cullen discuss the government's abandonment of its promise to change the voting system. 9:05

Trudeau invokes stability, lack of consensus

In question period, NDP Leader Tom Mulcair called Trudeau's actions a "massive political deception."

In response, Trudeau pointed to a difference of opinions among the major political parties.

"As people in this House know, I have long preferred a preferential ballot. The members opposite [in the NDP] wanted proportional representation. The Official Opposition wanted a referendum," he said, gesturing toward the Conservatives.

"There is no consensus. There is no clear path forward. It would be irresponsible to do something that harms Canada's stability."

Later, in response to a question from May, Trudeau expanded on his explanation.

"Anything a prime minister or a government must do must be in the interest of Canada and all Canadians, particularly when it comes to transforming our electoral system. I understand the passion and the intensity with which the member opposite believes in this and many Canadians mirror that passion and that intensity."

"But there is no consensus, there is no sense of how to do this. And, quite frankly, a divisive referendum, an augmentation of extremist voices in this House, is not what is in the best interests of Canada."

While electoral reform was ruled out, Gould's mandate letter includes several objectives, including a review of "risks to Canada's political and electoral activities from hackers," new regulations for political fundraising, the creation of an independent commission for election debates and new measures to limit spending by parties between elections.