Former Conservative Prime Minister Stephen Harper endorsed candidate Pierre Poilievre to be the next party leader.

In a rare public return to party politics, Harper released a short video on Twitter expressing his support for Poilievre.

Harper said in his appearance that the race for party leadership is full of candidates, but one stands out.

Explaining that Poilievre served as a strong minister under his leadership when the Conservatives were last in power, before being defeated by Liberal Prime Minister Justin Trudeau in 2015.

Harper also said that Poilievre has spent the past few years in opposition being "the most outspoken and effective critic of the government."

And he says Poilievre spoke about pressing economic issues like debt and inflation, and offered solutions "rooted in sound conservative ideas."