How the NDP's deal with the Liberals died

On the same day the Liberal government's House leader told reporters she was "confident" her party's governance agreement with the NDP would last until June 2025, NDP Leader Jagmeet Singh was busy recording a video in front of Parliament saying he was killing the deal.

"I'm fairly confident that agreement is a good agreement, it's a strong agreement and we'll get to the end of June," Karina Gould told an early morning news conference at the federal cabinet retreat in Halifax on Aug. 27.

One week later, Gould and the rest of the Liberal cabinet were hit with a political bombshell that caught them completely by surprise — when the NDP pulled out of the confidence-and-supply agreement that was set to keep the Liberal minority government in power through to next June.

The decision could see the government toppled before fall 2025 and introduces a new degree of instability to the coming sitting of the House of Commons, set to start Sept. 16.

Several NDP and Liberal sources spoke to CBC News about the final days of the deal and the NDP's closely guarded secret plan to blow it up ahead of its stated end-date of June 2025.

The sources spoke on the condition they not be named, as they were not authorized to speak publicly about internal party operations. CBC News agreed to that condition in order to get a better understanding of the decision and the timeline of events.

The NDP had been hammering out the details of their plan to leave the deal for at least a month before Singh's video was released. Some NDP staffers and MPs said the deal was tying the NDP to a toxic Liberal brand polling up to 20 percentage points behind Pierre Poilievre's Conservatives.

Sources also said New Democrats believed they'd achieved all they could from the agreement.

That opinion was echoed by NDP House leader Peter Julian, who spoke to CBC's chief political correspondent Rosemary Barton in an interview airing Sunday.

"It's fair to say, members of caucus understood we've kind of hit this limit in what the Liberals are prepared to do," said Julian.

Sources told CBC News the party's decision to break the agreement was largely settled by Singh early in the summer, a full year before it was supposed to end.

A senior NDP source said that in June, as the spring sitting of Parliament was wrapping up, "there was a discussion about, this is probably as much as we are going to get. It's probably time to end the agreement and move on — and then it was just kind of putting together the how and when of it all."

"People were saying, 'We've got to get out,'" another senior source said. "But it wasn't hard and fast at that point."

A source said there was "a final conversation" with caucus in June where MPs were told "the likely scenario here is that this agreement is ending ... [and] then we just kind of got to work on figuring out what that all looked like."