Canadian leader Justin Trudeau apologized Thursday for a rare lapse in his unflappable, everyman persona after responding with heavy sarcasm to indigenous protestors who interrupted him at a party fundraiser.

The normally suave prime minister was speaking at a Liberal Party event in Toronto on Wednesday when the activists unfurled a banner and began chanting slogans against mercury poisoning in a river where they fish.

“Thank you very much for your donation,” Trudeau called after the Grassy Narrows First Nation demonstrators as they were being thrown out, aware that they would have had to pay to get in.

“As we know, the Liberal Party is filled with different perspectives and different opinions and we respect them all,” Trudeau immediately added, an apparent acknowledgment that he had overstepped.

He was shouted down by angry audience members before he could finish, however.

The reaction — caught on a video which went viral on social media — was in stark contrast to Trudeau’s usual show of compassion and grace when confronted by protestors.

“From time to time, I’m in situations where people are expressing concerns or protesting a particular thing, and I always try to be respectful and always try to engage with them in a positive way,” Trudeau told reporters in Halifax on Thursday.

“I didn’t do that last night. Last night I lacked respect towards them and I apologize.”

The government pledged in late 2017 to help fund the construction of a mercury treatment facility for people exposed to the toxic metal over the past 50 years.

But the protestors said their community in northern Ontario is still waiting for that money 500 days later and worry that with an election drawing closer the promise will not be fulfilled.

Trudeau said he has directed his indigenous services minister to follow up on the matter.