The premier was also pressed on what exactly would constitute a "fair deal," especially if Washington maintains some tariffs on Canadian vehicles. Asked whether he could accept an agreement that leaves U.S. tariffs of roughly 10 to 15 per cent on Ontario-made vehicles while Canada drops its retaliatory tariffs on American autos, Ford indicated he would not support a one-sided arrangement.

The most intense disagreement came over a question that has particular resonance for a party that has spent the past eight years trying to recover from its collapse in 2018: does its next leader need to be sitting in the legislature?

One potential area of movement involves Canada's supply management system.

While supply management has long been a source of friction between Canada and the United States, industry sources now say that American negotiators are not currently demanding that Canada dismantle the system.

Chief Electoral Officer Greg Essensa rejected the request, saying Elections Ontario does not have jurisdiction over government advertising.