BRAMPTON, Ontario — Canada’s Conservative Party leader arrived in his campaign bus for a rally in the Toronto suburb of Brampton as a sparse crowd of about 150 milled about the venue, a largely empty parking lot.

Party workers gently herded the spectators toward a small stage in a bid to make the meager turnout for the leader, Andrew Scheer, appear larger for cameras. Afterward, many of them swarmed the small stage to pose for selfies with Mr. Scheer, the only politician who has a realistic chance of toppling Prime Minister Justin Trudeau in the country’s Oct. 21 election.

“He was slow off the mark getting started, getting his message out there. But I think it’s coming across pretty good now,” said John Sanderson, a former municipal councilor, while campaign workers began dismantling the tents, lights and speakers. “He’s obviously becoming more confident and, you know what, I think he’s got a good shot.”

[Canadians have elected a Liberal minority government, granting Justin Trudeau a second term as prime minister.]