The party and the Liberals signed an agreement in March 2022 that secures NDP support for the minority Liberal government in exchange for a commitment to act on key NDP priorities. That agreement is slated to be in place until 2025.

In an interview on Rosemary Barton Live airing Sunday, Broadbent said that bumps up close against the next scheduled federal election.

"It's a 'getting credit' issue," he told CBC chief political correspondent Rosemary Barton of the deal. "The good things that are there, and there are many good things, Liberals of course will be taking credit."

"It's a matter of having time for us, for the NDP, to make its voice known. So maybe if the agreement were a year shorter, it might be a little better."

The supply and confidence agreement includes, among other initiatives, commitments to act on dental care, universal national pharmacare and housing.

Broadbent does, however, praise Singh and Prime Minister Justin Trudeau for building security mechanisms into the agreement that, he says, were sorely missed in the failed 2008 coalition agreement between the NDP and the Liberals that he helped negotiate.

The current agreement includes quarterly meetings between Singh and Trudeau and monthly 'stock-take' meetings by an oversight group tasked with monitoring overall progress on key commitments.

2008 deal 'a mistake'

Broadbent sat down with Barton to discuss his new book Seeking Social Democracy: Seven Decades in the Fight for Equality, which includes a frank assessment of the 2008 Liberal-NDP coalition agreement.

"I have since come to think that the coalition agreement was a mistake," Broadbent says in the book.

"We saw an opening to oust Stephen Harper and bring in a progressive agenda in response to the economic situation, which in principle seemed like a good idea," said Broadbent. "But we got it wrong."

Following then-Conservative Finance Minister Jim Flaherty's fall economic update in 2008, the Liberals and the NDP negotiated a coalition agreement to oust the minority Conservatives from power. That agreement included a written pledge of support from the Bloc Québécois because the Liberals and the NDP didn't have enough combined seats to form a majority government.

But before the three parties could bring down the government in a vote of confidence, Governor General Michaëlle Jean, at the request of Prime Minister Harper, agreed to prorogue Parliament, effectively delaying the vote of confidence.

The proroguing of Parliament and resignation of Liberal Leader Stéphane Dion ended any prospect of a Liberal-NDP coalition government in 2008. (Adrian Wyld/The Canadian Press)

By the time Parliament resumed, Stéphane Dion had resigned as Liberal leader and his successor, Michael Ignatieff, had agreed to support a new Conservative budget — ending any prospect of a Liberal-NDP coalition government.

"With all the advantage of hindsight, it probably was a mistake to try to negotiate with someone that was in such a weak political position," Broadbent told Barton, referring to Dion.

Broadbent also writes in the book that the parties involved in the coalition attempt failed to predict Harper's "wicked and misleading attack on the agreement."

Harper was "practising very devious politics indeed when he attacked that process as being illegitimate," Broadbent said in the interview.

"He portrayed them as being anti-democratic and that's totally ridiculous. Coalitions are very democratic."