Stephen Lewis, the former leader of the Ontario NDP who spent decades fighting the HIV/AIDS epidemic with the United Nations and through his own foundation, has died.

Mr. Lewis, 88, passed away in Toronto on Tuesday, just days after his son, Avi, was elected leader of the federal NDP.

He had been battling cancer and was in a hospice, according to his sister, Janet Solberg.

“He waited for his son to win. I’m not joking. He never lacked for willpower,” Ms. Solberg said.