Canada

Photo: The Canadian Press. All rights reserved.

Marc Garneau, left, and Justin Trudeau take part in a Liberal leadership debate in Mississauga, Ont., on February 16, 2013. Garneau is challenging Trudeau to a one-on-one debate. THE CANADIAN PRESS/Chris Young

Liberal leadership hopeful Marc Garneau is challenging front-runner Justin Trudeau to a one-on-one debate.

The Montreal MP threw down the gauntlet Monday, arguing that Trudeau has undermined his own credibility and that of the Liberal party by speaking only in "vague generalities" thus far.

"It is time for Justin to step up and defend his ideas because if he can't defend them to me in front of a room full of Liberals, he will never be able to do it against (Prime Minister) Stephen Harper," Garneau told a news conference.

"The leadership of the Liberal party is too important a position to be handed to an untested candidate who is hiding behind a carefully crafted public relations campaign."

Trudeau quickly rebuffed the challenge.

"I respect all the candidates" running for the Liberal leadership, he said via Twitter.

"See you in Halifax, Marc. I hear there are 1 on 1s."

He was referring to the fourth of five all-candidates' debates, which is scheduled to take place Sunday in Halifax. It will include a series of one-on-one encounters among the contenders, as did the last debate in Mississauga.