HALIFAX -- Prime Minister Justin Trudeau reminded a large town hall audience in Nova Scotia that he and U.S. president-elect Donald Trump rode to power through committing to help the middle class, though he conceded working with the new regime is going to present challenges.

Talking in the centre of a hockey rink before about 3,000 people in Dartmouth, N.S. on Monday, Trudeau responded to a question from an audience member who asked whether he expects he'll have to resist some of the Republican president's policies.

Trudeau responded by saying both Canadian and American middle-class jobs depend on a good relationship between the prime minister and the U.S. president.

"As different on some levels as my approach is from the incoming president ... we both got elected on a commitment to help the middle class and we're going to be able to find common ground on doing the kinds of things that will help ordinary families right across the continent," he said.

He also said it will remain important for him to remind the American administration that Canada will retain certain policies such as openness to refugees and a gender-balanced cabinet.

"We're going to stay true to who we are. ... Is it going to be a challenge? Sure," he said.

The town hall began more than 40 minutes late to allow people time to be seated. Once it started, the tone was largely friendly until one woman asked about green energy.

"That oil has to stay in the ground," said a woman who indentified herself as Mi'kmaq.

"Why do you guys constantly bring up all these oil pipelines?"

Trudeau told the woman that we are "going to have to agree to disagree on the issue." As he tried to say that 39 indigenous communities in Western Canada are supportive of the Kinder Morgan pipeline, he was interrupted by the word "lies."

Trudeau stopped in his tracks and asked for respect.

"A little respect please, I'm giving you as much respect as I can and I'm asking for the respect back," Trudeau said as the audience applauded.

The prime minister also stirred up some criticism on Twitter when he answered a man's questions about the difficulties of being an immigrant.

"I'm a 10th or 11th generation Canadian on one of my sides, but my maternal grandfather was born in Scotland, so I do have some idea of the challenges it takes to come to Canada," he said.

"I've always been first of all jealous of those Canadians who got to say 'I chose Canada.' Canada was chosen for me. And anyone who chooses to leave home, cross an ocean or two and start life in a brand new place ... is exactly the kind of people we want to welcome into this country."

Some Twitter commentators criticized Trudeau for claiming to know the immigrant experience based on his grandfather's journey to the country at a young age.

Some members of the audience also expressed concerns about the basic problems in their day-to-day lives, such as the crumbling infrastructure in local hospitals.

"We hear you're planning on spending on infrastructure, so I was wondering if you can help replace our aging hospital systems?" asked one man in the audience, referring to the Victoria General hospital in Halifax as being in "third-world condition."

Trudeau responded by saying he's going to work to improve relationships with provinces, but said the choices of what to spend money on in health will remain with the provinces.

"I don't think it should be the federal government that decide what the local priorities are," he said.

Retired Lt.-Gen. Romeo Dallaire, who has advocated for soldiers suffered from post-traumatic stress disorder, also was in the audience and urged Trudeau to help veterans who are struggling with health problems.

Earlier Monday, the prime minister faced questions from a radio host on News 95.7 about whether his government could do more to assist with soldiers struggling with post traumatic stress disorders, in light of a tragedy in northern Nova Scotia that saw a retired corporal with PTSD shoot his wife, their 10-year-old daughter, his mother and then himself.

Neither National Defence or Veterans Affairs have committed to investigate the treatment Lionel Desmond received before and after his release from the military.

Trudeau didn't address the possibility of an inquiry, but said he's committed to supporting veterans.

He cited the party's reopening of veterans' service centres across the country and the federal offer to provinces to provide additional funding for mental health services.

"We know there's more to do ... and as this tragedy with Cpl. Desmond highlights, there is a need for much more work on PTSD," he said.

"We need to do a better job supporting people struggling with mental health issues."