With the Ontario Liberal Party (personal disclosure – I’m a member) beginning the process of selecting a leader, it is an appropriate time to think more broadly about Ontario politics. In the last 80 years – the post-World War II era – the PC Party has formed the government for 55 years (69 percent of the time), with the Liberals governing from 1985 to 1990 and 2003 to 2018 (25 percent of the time), and the NDP governing from 1990 to 1995 (6 percent of the time).

It is reasonable but personally uncomfortable to conclude that the PCs are the “natural governing party” of Ontario. The PCs have rarely won a majority of the popular vote but most of the time have won from 40 to 45 percent. Together with the opposition parties dividing the rest of the vote reasonably evenly, this means the PCs have usually won majorities of the seats in the Legislature. The PCs have become a counterpart to the federal Liberals, who have governed for 48 years in the same period, and are considered to be Canada’s “natural governing party.”

Electoral Reform?

If Ontario used some variant of proportional representation, no party would receive a majority of the seats in the Legislature. It is likely that one of the three progressive opposition parties (Liberals, NDP, Greens) would form a government with the support of the other two. In the last election campaign, the NDP and Greens included electoral reform in their platforms, but the Liberals didn’t. I expect that it will be one of the issues in the Liberal leadership campaign. Say that, with a new leader, the Liberals join the NDP and Greens in supporting electoral reform. The three parties would still have to win enough seats under the current rules to relegate the PCs to a minority, form a progressive minority government, and then pass electoral reform legislation. First past the post favours the PCs, so they will not change it. Indeed, they are tweaking some electoral rules to make it more likely they will continue winning legislative majorities – by abolishing fixed election dates (which, to be sure, they ignored this year) and increased political donation limits.

A Temporary Coalition?

The political scientist Maurice Duverger propounded a “law” that, in a first past the post electoral system, parties are likely to merge to the point that there are two major parties. Laws in political science are empirical generalizations, unlike like those in the natural sciences, which are deductions from first principles. Ontario stands out as an exception to Duverger’s Law.

Some commentators and activists imagine that the three progressive parties could defeat the Conservatives by forming a temporary alliance that, in effect, implements Duverger’s Law. They envision that the three progressive parties will agree to run only one candidate in competitive constituencies or that their supporters will vote strategically. This would prevent a PC majority and enable the progressive minority government that would institute electoral reform.

After the recent Ontario election, I posted a blog pushing this thinking a step farther and imagined that the three progressive parties form an alliance that I dubbed the Ontario Renewal Party (ORP). And I imagined that the PC Party would respond to this development by absorbing fringe right wing parties such as New Blue and the Ontario Party. I called the right-wing alliance the PC+ Party. In this scenario, the ORP would win a narrow victory, 70 to 54 seats. The scenario also showed that the two bigger partners of the ORP, the Liberals and NDP, often need votes from the Greens to win seats, just as the PC+ Party often needs votes from the right-wing fringe parties.

The narrowness of the win for the ORP in my thought experiment shows that, if the actual PC Party wins 40 to 45 percent of the vote, it is unlikely that strategic voting by the supporters of the three progressive opposition parties would be enough to deprive the PC Party of their majority in the Legislature. I expect that, for strategic voting to work, it would be necessary for the PC Party to have much less support, say closer to 35 percent.

What are the chances that the Liberals and NDP could increase their support so significantly that the PC Party could drop back to the 35 percent range? First, consider the NDP. In the last election, its share of the popular vote fell from 24 to 19 percent, but its vote was distributed so efficiently that it lost only four seats relative to the 2022 election. Its leader, Marit Stiles, is staying on, with an unenthusiastic endorsement (68 percent approval) in a recent leadership review. Nonetheless, the absence of a Liberal leader will give her more media attention over the next year.

The Liberals received 30 percent of the vote in the 2025 election, but very inefficiently distributed. To defeat the PC Party by forming a Liberal minority government, the new Liberal leader will have to do considerably better. If the NDP vote in 2025 represents its core vote, then it is unlikely that a new Liberal leader would take many votes from the NDP. Even if the Liberals did take votes from the NDP, they would win NDP rather than PC Party seats, which would not affect the PC Party’s majority. The place for a new Liberal leader to look for votes is from supporters of the PC Party, so that the Liberals could flip PC Party seats.

As we watch candidates for the Liberal leadership declare themselves, we should evaluate their policies and personas in terms of whether they are hoping to take votes from the PC Party or from the NDP. I will have more to say about this in coming months.