The first of two official election debates takes place tonight, with five federal party leaders facing off in what may well be their best chance to sway voters before election day on Sept. 20.

With less than two weeks to go, millions of voters are expected to tune in for tonight's two-hour French debate and Thursday's English debate.

Liberal Leader Justin Trudeau, Conservative Leader Erin O'Toole, NDP Leader Jagmeet Singh, Bloc Québécois Leader Yves-François Blanchet and Green Party Leader Annamie Paul will participate in both debates.

People's Party of Canada Leader Maxime Bernier did not meet the criteria established by the independent leaders' debate commission for participation.

Both debates, organized by consortiums of broadcasters, are being held at the Museum of Canadian History in Gatineau, Que., just across the river from Parliament Hill.

The debates come as opinion polls suggest the Liberals and Conservatives are stuck in a tight two-way race, with the NDP and Bloc poised to determine which of the two main parties emerges victorious.

Tonight's French debate begins at 8 p.m. ET.

Topics to be discussed are climate change, the cost of living and public finances, Indigenous Peoples and cultural identity, justice and foreign policy, and health care and the COVID-19 pandemic.