Marc Garneau is challenging Justin Trudeau to a one-on-one debate.

"The leadership of the Liberal Party is too important a position to hand to an untested candidate hiding behind a carefully crafted public relations campaign," Garneau said at a news conference Monday morning.

In his remarks, the candidate for the leadership of the federal Liberal Party said the format of candidate debates so far has been too limiting.

There have only been three minutes of one-on-one debate between himself and Trudeau, Garneau said of their "fleeting moments of substantive debates and discussion."

And in those minutes, he said, they have barely scratched the surface.

Waiting for the next Liberal leader to detail his or her policies once in office would be too late, Garneau said, suggesting that the party's top job is too important to have candidates defend their positions after the fact.

When asked to explain how his own campaign, with its own public relations strategy, differs from Trudeau's, Garneau said he is unafraid to detail the specifics of his policy positions.

Trudeau needs to do the same, Garneau said, "much more clearly, in much more detail... and that's why I'm calling for this debate."

It didn't take Trudeau long to reply Monday. The Montreal MP took to Twitter to suggest he was looking forward to a more intimate-style of debate at the next meeting in Halifax, which is taking place on Sunday.

"I respect all the candidates for #LPCldr. See you in Halifax, Marc. I hear there are 1 on 1s. ;-)," Trudeau wrote.

There are a total of nine candidates for the federal Liberal leadership -- including MPs Joyce Murray, Martha Hall Findlay and Martin Cauchon, as well as lawyers David Bertschi, Deborah Coyne, George Takach and retired Lt.-Col. Karen McCrimmon -- but Trudeau is widely seen as the frontrunner.

"I believe most of the polls show me as being ... the second," Garneau said.

Such a debate would likely happen outside the Liberal Party's strictures, he added, explaining that the format for the five all-candidates' debates has been long-decided.

Garneau said his call for a one-on-one with Trudeau should not be seen as a jab at the Liberal Party.

"They have a situation where they have to deal with nine people who have followed the rules, they're in the race, and there's a limited amount that they can do. What I'm doing is saying we need more."

The others can "throw down the gauntlet" if they choose, he added.

"I'm doing it because I believe it's important."

In the event Trudeau accepts the challenge, Garneau said he envisions an hour-long debate, moderated by a "very objective journalist," in a format that echoes the presidential campaign debates between Barack Obama and Mitt Romney last fall.

Having the candidates present their ideas and then debate them, he said, would let Canadians evaluate them both "in terms of leadership and also in terms of ideas."

So far, the Liberal Party has held leadership debates in Vancouver, Winnipeg and the Greater Toronto Area. The next is slated for March 3 in Halifax, with the final debate in Montreal on March 23 ahead of the vote in April.