Cardinal issued a statement on Thursday saying he will be stepping down as the party's candidate in Edmonton Centre "due to personal and health reasons" without specifying what those reasons are.
It was just a few weeks ago that federal NDP Leader Tom Mulcair made a stop in Edmonton to mark Cardinal's nomination.
Cardinal says it was a difficult decision to make but says he's hopeful "a strong candidate will step forward" to replace him.
There had been hope within the party that Cardinal might have a shot at the riding because the incumbent, Tory Laurie Hawn, is not running.
Alberta's only NDP member of Parliament, Linda Duncan, had called it a "priority riding" for the party.
Cardinal's website lists a long track record of public service including being a founding board member of Racism Free Edmonton; executive board member of the John Humphrey Centre for Peace and Human Rights; founder of the Indigenous Peoples’ Art and Culture Coalition; and board member of Little Warriors.