HALIFAX -- Liberal Leader Justin Trudeau on Wednesday defended a large indoor rally he held in Brampton, Ont., saying his party followed public health guidelines.

Hundreds of people surrounded the stage at Tuesday evening's event, where he was introduced by 87-year-old former prime minister Jean Chretien.

Supporters mobbed Trudeau at the end of the event, despite organizers asking people to stand in squares taped on the ground.

Liberal staffers said there were about 400 people in attendance and the gathering met local COVID-19 rules limiting indoor venues to half capacity.

On Wednesday, Trudeau was asked about the wisdom of holding such a large indoor event, which was also attended by 100-year-old former Mississauga, Ont., mayor Hazel McCallion.

"First of all, nobody tells Hazel McCallion or Jean Chretien what to do or what not to do," he told reporters in Halifax.

"I was so glad they chose to come join us in that event, which followed all public health guidelines."

Trudeau says it's important to recognize that nearly 80 per cent of eligible Canadians are vaccinated.

"And that means that for those people, being able to go back to doing the things we love is more and more a possibility."

Speaking in Quebec on Wednesday morning, Conservative Leader Erin O'Toole criticized Trudeau for holding the event "in defiance of common sense and social distancing guidelines," noting that Brampton has been a COVID-19 hot spot.

Trudeau, meanwhile, continued to hammer back at O'Toole for failing to require his candidates be vaccinated against COVID-19.

Both Chretien and Trudeau delivered separate speeches on a stage in the middle of a Brampton convention centre ballroom, surrounded on all sides by an enthusiastic crowd that cheered as they criticized the other party leaders and promoted the Liberal platform on vaccines, the environment and child care.

In his speech, Chretien defended Trudeau's decision to send Canadians to the voting booths, saying that election calls are "a tradition" for minority governments after two years.

He delivered spirited criticism of O'Toole and Bloc Quebecois Leader Yves-Francois Blanchet, and said Canadians need a centrist government to face issues such as climate change and the challenges posed by China.

"It's not the time to move to the far right or the far left, it's the time to be in the middle," he said.

When asked later if he had felt comfortable in the middle of a large crowd, Chretien admitted he hadn't known about the format ahead of time.

"I had no podium and so no, it wasn't the surrounding I'm used to," said Chretien, who added that he'd been vaccinated.

"But I'm happy that I came. I've been around the track for a while, and to be back on the track wasn't too bad."

McCallion said after the event that the crowds were just one of the reasons why an election shouldn't have been called during a pandemic.

"The governments have been saying, stay at home, stay away from getting in groups, and then an election is called that brings people together in groups," McCallion said.

Despite her criticism of the election call, McCallion also recognized that minority governments "don't work," and said she hoped Trudeau's Liberals would win a majority on Sept. 20.

Later, at a stop at a brewery in Fredericton, N.B., Trudeau told supporters that ensuring as many people as possible get vaccinated remains the only way to end the COVID-19 pandemic.

"I know as good Liberals, you guys are probably all vaccinated but you all know people who haven't yet been vaccinated or are still hesitating," he said. "It's time for them to get vaccinated as well."

Trudeau said that O'Toole, by defending the choice of people who choose not to get vaccinated, is impacting Canadians' "freedoms and abilities" including putting the country at risk of further lockdowns.

Campaigning alongside Jenica Atwin, a former Green MP who crossed the floor to join the Liberals, Trudeau also touted the Liberal climate plan and said neither the NDP or Green Party have stepped up with a "real and ambitious plan" to fight climate change.

This report by The Canadian Press was first published Sept. 15, 2021.