OTTAWA — Prime Minister Justin Trudeau’s decision to call an election two years ahead of schedule has not worked out as planned.

Polls have consistently tracked a decline in voter support for his Liberal Party and a rise in backing for its nearest rivals, the Conservatives, leaving the parties in a statistical tie.

The bulk of the 36-day campaign, the shortest allowed by law, came during Canada’s all-too-brief summer, when many voters’ minds were far from politics. The Taliban takeover in Afghanistan, where the Canadian military fought, further distracted the public’s attention.

So for Mr. Trudeau and his rivals, particularly Erin O’Toole of the Conservatives, the debates this week in each of Canada’s official languages were crucial opportunities to define the campaign before Election Day, Sept. 20.

Jagmeet Singh, the leader of the left-of-center New Democratic Party; Annamie Paul, who heads the Green Party; and Yves-François Blanchet of the Bloc Québécois, a regional party that endorses Quebec’s independence. With the five leaders receiving equal time, it was difficult for any to break through with a detailed message.

The French-language debate on Wednesday often focused on issues of interest to Quebec. With English being the language of three-quarters of Canadians, the debate on Thursday in that language was considered the more important of the two.