Mr. Trudeau has many achievements since 2015 to point to. His government has introduced carbon pricing and other climate measures, legalized cannabis, increased spending for Indigenous issues, and made 1,500 models of military-style rifles illegal. A new plan will provide day care for 10 Canadian dollars a day per child.

Though his popularity has diminished, Mr. Trudeau’s star power remains. When he dropped by the outdoor terrace of a cafe in Port Coquitlam, an eastern suburb of Vancouver, for elbow bumps, quick chats and selfies with voters, a crowd soon swelled.

“We love you, we love you,” Joy Silver, a 76-year-old retired schoolteacher from nearby Coquitlam, told Mr. Trudeau.

But as Election Day nears, many Canadians are still asking why Mr. Trudeau is holding a vote now, two years ahead of schedule, with Covid-19 infections on the rise from the Delta variant, taxing hospitals and prompting renewed pandemic restrictions in some provinces or delaying their lifting in others.

Also criticized was that he called the vote the same weekend Kabul fell to the Taliban, when Canadian troops were struggling to evacuate Canadians as well as Afghans who had assisted their forces.

“They’ve been struggling with answering that question the whole campaign,” said Gerald Butts, a longtime friend of Mr. Trudeau’s and a former top political adviser. “And that’s part of why they’re having trouble getting the message across.”

Mr. Trudeau has said that he needs to replace his plurality in the House of Commons with a majority to deal with the remainder of the pandemic and the recovery that will follow — although he avoids explicitly saying “majority.” The Liberal Party’s political calculation was that it was best to strike while Canadians still held favorable views about how Mr. Trudeau handled pandemic issues, particularly income supports and buying vaccines.