Quebec Premier Christine Fréchette has kicked off a high-stakes election campaign that will likely be dominated by the Canada-U.S. trade war and the prospect of a third referendum on independence.

Ms. Fréchette, who has been premier since April, visited Quebec’s lieutenant governor Thursday morning to dissolve the National Assembly and launch a 39-day campaign. Quebeckers will go to the polls on Oct. 5.

The start of the campaign comes days after trade negotiations between Canada and the U.S. fell apart, prompting U.S. President Donald Trump to approve 50-per-cent tariffs on about $28-billion worth of Canadian goods, while Ottawa responded with what it called dollar-for-dollar tariffs Tuesday.

Ms. Fréchette is attempting to position her party, the Coalition Avenir Québec, as the best choice to lead the province at a time of geopolitical uncertainty. But after eight years in government, mostly under the leadership of former premier François Legault, the CAQ has seen its support collapse in recent years as Quebeckers look for change.