The main rivals to Canada’s Liberal prime minister, Justin Trudeau, said a threat that forced him to wear a bulletproof vest at an election rally was a concerning sign for the country’s democracy.

Trudeau arrived 90 minutes late to the rally outside Toronto wearing bulky protection under his shirt, a Reuters witness said, after receiving a security threat.

Andew Scheer, the Conservative party leader, said late on Saturday that it was “very upsetting to hear that Justin Trudeau had to wear a bulletproof vest tonight at a campaign event. Threats of violence against political leaders have absolutely no place in our democracy.”

Scheer is Trudeau’s main rival in the federal election on 21 October and the two are in a statistical tie nationally, according to polls. But the left-leaning New Democratic party is gaining and could end up with the balance of power.

The NDP leader, Jagmeet Singh, said: “Any threat made against Justin Trudeau, or any leader, is troubling to all of us. No matter how you vote or believe, no one should face threats of violence.”

Trudeau was going ahead with plans to campaign in York, Ontario, on Sunday, said a Liberal official who declined to be named.

At the Saturday rally, Trudeau still plunged into the crowd to shake hands and pose for photos as he usually does, but unlike in the past he was surrounded by bodyguards wearing large backpacks.