After the NDP's fury over the Liberals' decision not to pursue electoral reform, Green Party Leader Elizabeth May stepped to the mic and delivered an assessment that can cut more sharply than anger: she's disappointed.

In fact, May was downright sorrowful, calling the move the worst government betrayal of her adult life.

May fought to become a voting member of the special committee on electoral reform and travelled the country along with the other MPs on the committee, spending weeks away from their families and ridings last summer. All after getting reassurances from senior Liberals, she said, that they were serious about reform.

The NDP, who have promised electoral reform for decades, persuaded the Liberals to give up their majority on the committee and add May, along with a Bloc MP and an additional New Democrat, rather than sticking to the traditional proportions based on seats in the House.

It now seems all of that negotiation, study, money and effort -- including by those who presented at or wrote to the committee -- meant nothing.

Despite a clear promise that the 2015 election would be the last one under the current first-past-the-post system, Democratic Institutions Minister Karina Gould announced Wednesday that there was no consensus on electoral reform, and therefore the government won't pursue it.

"It was never a betrayal when Stephen Harper did the very worst thing [for the environment]. But when you believe in someone and they let you down, that's much harder," May said, her voice breaking.

Further, May said, "As a women leader of a federal political party in this country, I am deeply ashamed that our feminist prime minister threw two young women cabinet ministers under the bus on a key election promise, that he left them twisting in the wind and not fulfilling [the promise]."

That's a theme NDP democratic reform critic Nathan Cullen picked up on too, describing his meeting Tuesday with Gould, at which he said there was no sign this was about to happen.

"It's, I don't know, fear when the prime minister phones and asks you to be the democratic institutions minister, because you're about to watch your career get torpedoed and put up as the face of a government preparing to lie to Canadians," Cullen told reporters outside the House of Commons.

"I personally feel for the new minister. I thought Mr. Trudeau was a tough guy and he'd be out here himself defending this about-face, but apparently not so much," he said.

The Conservatives were silent on the issue, after having pushed for a referendum on whether Canadians wanted electoral reform.

It's not surprising the sting is most painful for the NDP and Green Party. As both May and Cullen pointed out, progressive voters were encouraged to vote strategically for the Liberals in the last election partly because of the promise a Liberal government would revamp the system, theoretically making it easier to elect more New Democrat and Green representatives.

The Liberals are likely wagering not enough people care about the issue to make it stick, particularly not until the next election in the early fall of 2019. Whether it does could depend on the NDP's ability to convince progressive voters not to trust the Liberals again, says Shachi Kurl, executive director of the Angus Reid Institute.

They'll have to tell voters who abandoned the party in 2015 "look, this guy doesn't keep his promises, you strayed, you went to Trudeau, and we understand, but now it's time to come back to the NDP because this guy broke his promise," Kurl said.

She added that while polling suggests Canadians see the benefit of different voting systems, electoral reform isn't a priority for most of them. It didn't decide the last election.

"The 2015 election was about getting rid of Stephen Harper and the Conservatives," Kurl said. "Electoral reform will probably not be the deciding factor in the 2019 election."

May and Cullen predict that isn't the case. And they may have an advantage: Gould is a rookie MP with little political experience. The MPs who sat on the special committee and are now her main critics have spent years in Parliament and years campaigning for electoral reform. Their passion carried their news conferences.

Gould says she's up for the challenge.

"I'm so honoured to be the youngest female cabinet minister in Canada's history, and I think I bring a particular perspective to the table," the 29-year-old told CTVNews.ca. "I am so passionate about the democracy that we have here in Canada, and passionate about protecting it and enhancing it, and increasing accessibility."

Cullen promised he's not going to let it go.

"Our determination is doubled today that Mr. Trudeau will certainly pay a political price with those he lied to ... yet also the more broad promise he would be a different kind of politician. He will pay that political price."