Justin Trudeau has chosen to absorb a first barrage of Conservative attack ads that portray him as a political dilettante, stating he will not get engaged in tit-for-tat negative advertising.

The newly crowned Liberal Leader said his party has just started to develop its own advertising campaign, which he promised will offer a positive contrast to the agenda of the Conservative Party.

Liberals have long feared the Conservative Party's ability to use its war chest to define its adversaries in the eyes of the public through negative advertising, but Mr. Trudeau took it all in.

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He said that Canadians are tired "of negativity, of bullying, of cynicism," adding "the Conservatives are going to discover that the one thing they know how to do really well is no longer working for them."

The Conservative Party of Canada went on the offensive Monday morning with ads featuring Mr. Trudeau in a mock striptease and slow-motion shots of him wearing long hair and a mustache.

The first footage was taken during a fundraising event for the Canadian Liver Foundation, while Mr. Trudeau grew the facial hair as part of the Movember charity campaign.

"Does he have the judgment to be Prime Minister?" asks one of two English-language ads, with carousel music playing in the background.

Another ad emphasizes Mr. Trudeau's past work experience as a camp counsellor and drama teacher, adding he has had a lousy attendance record in the House of Commons since becoming a Liberal MP in 2008.

A spokesman for the Conservative Party defended the use of the footage from a charity event.

"We believe Justin Trudeau's eagerness to perform a striptease, regardless of the venue or putative cause, says something about his judgement," Fred DeLorey said in a statement.

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Scrumming with reporters in the foyer of the House, however, Mr. Trudeau said that he was happy to have offered his shirt to the Canadian Liver Foundation.

"I hope that all the attention drawn to that today and my willingness to have a little fun with it will actually lead them to receive more donations," he said.

Mr. Trudeau auctioned off a lunch for $1,900 at the charity event called What a Girl Wants in 2011.

"The Foundation believes Mr. Trudeau should be applauded for his commitment to an important health issue that affects an estimated 3.4 million Canadians," the charity said in a statement.

One of the Conservative ads quotes a 14-year-old interview with CTV in which Mr. Trudeau states that "Quebeckers are better than the rest of Canada."

The full-length quote shows that Mr. Trudeau was explaining why his father, former prime minister Pierre Trudeau, rejected any any distinct status for Quebec in the Canadian Constitution.

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"The quote they used is one in which I was actually talking about my father's philosophy of Quebec not needing special treatment," Mr. Trudeau said.

Still, Mr. Trudeau acknowledged that some of his past statements could have been expressed more coherently.

"I've had a microphone in front of my face since the age I was about four or five years old," he said.

"So there's an awful lot of things that they're going to try and bring up."

The advertising is the first sign of a new competitive era in federal politics, with the Liberal Party and the NDP both launching sharp attacks in the House against the Conservative government after a two-week Easter break.

NDP Leader Thomas Mulcair ratcheted up the pressure against the growing use of temporary foreign workers in Canada, blaming the government for the arrival of cheap labour in various sectors of the economy.

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"We have 1.4 million Canadians without work. They want to know why their jobs are being taken by temporary foreign workers," Mr. Mulcair said.

Prime Minister Stephen Harper promised to reform the program, and went on to reject Mr. Trudeau's charges that the government is hurting the middle class by raising tariffs on imports from countries such as China.

Speaking to reporters, Mr. Mulcair said that he would not be dragged into the advertising battle between Liberals and Conservatives.

With a smile, he added: "If there is one thing that my staff doesn't have to fear, it's the possibility that I would be involved in something in which I take off my clothes."