NIAGARA FALLS, Ont. - The Prime Minister says his party will be able to recapture a southern Alberta riding in an upcoming byelection, despite the fact that a Liberal hasn't been elected to that seat in nearly half a century.

Justin Trudeau made the bold prediction in his opening address Friday at the federal Liberal Party's Ontario wing convention in Niagara Falls, Ont.

He said he visited Medicine Hat, Alta., earlier this week in advance of Monday's byelection in the riding of Medicine Hat-Cardston-Warner.

Trudeau's visit was an effort to boost the chances of Liberal candidate Stan Sakamoto, a local businessman.

Trudeau attracted about 2,500 people hoping to catch a glimpse of him.

He told Liberals on Friday that he had faith in Sakamoto's chances.