“He felt that in Canada the risk of violent protest was simply too high,” said Ryan Ruppert, president of promotions company Spectre Live Corp., which had booked Mr. Cheney for an April 24 appearance at the Metro Toronto Convention Centre.

In September, Mr. Cheney was speaking at a private club in Vancouver when protesters massed outside the front door harassing ticket holders and in one instance, choking a security guard. The former vice-president was reportedly held inside the building for more than seven hours as Vancouver Police in riot gear dispersed the demonstrators.