How much longer can the Liberal-NDP deal last?

On Thursday, Conservative Leader Pierre Poilievre made a great show — he even wrote a letter — of calling on NDP Leader Jagmeet Singh to walk away from the NDP's supply-and-confidence agreement with the Liberal government.

Poilievre alleged that Singh was sticking with the deal so that he could become eligible for a parliamentary pension (Poilievre qualified for an MP pension in 2010, when he was 31 years old).

For that reason, Poilievre said, "Canadians are now calling him 'Sellout Singh'" — the nickname Poilievre himself has given the NDP leader. (Poilievre's fondness for nicknames recalls a certain American presidential candidate.)

It's perhaps not a coincidence that Poilievre's call came in the midst of a byelection campaign in Elmwood–Transcona, a Manitoba riding where Conservatives have traditionally finished second to the NDP.

For that matter, Poilievre's broader interest in Singh no doubt has something to do with the fact that some of the Conservative Party's best hopes for gains in the next election are ridings in British Columbia and northern Ontario that are currently represented by NDP MPs.

Poilievre had barely finished speaking before the Conservative Party sent out a fundraising appeal, informing supporters that the Conservative leader had just "challenged" Singh "to PULL OUT of the carbon tax coalition."

In response, the NDP more or less shrugged, though they did allow that they could always walk away from the deal.

The historic supply-and-confidence agreement between the Liberals and NDP — the first such formal deal between two parties at the federal level, though there were provincial precedents — is now two and a half years old. And with that agreement underpinning the business of the House of Commons, the current Parliament is now the longest-lasting minority Parliament in modern Canadian history.

Of course, it's inevitable that the deal (and this Parliament) will eventually come to an end. Officially, the agreement between the two parties expires whenever the House chooses to adjourn for the summer in June 2025, ahead of what would be an election in October 2025.

(Technically, the Parliament of Canada Act allows for five years to elapse between elections, but governments have lately deferred to a 2007 law that, while non-binding, says elections should be called at least every four years.)

But if the end game is approaching, it sets up an interesting test of political and practical imperatives.

Poilievre's political imperative is fairly obvious: Ahead of the next federal election, he would like to yoke the Liberals and NDP together.

For the Conservative Party's purposes, it would surely help for the NDP to be associated with an unpopular government, and for the Liberals to be associated with a party that some centrist voters might consider too radical. 

The Liberals and NDP had good reasons to make a deal in March 2022, and they've both derived real benefits from doing so.