Liberal Leader Justin Trudeau has outlined his plan to improve Canada's relationship with the United States with a promise to end the "hectoring, belligerent" tone that he says has defined the Harper government.

In a speech to the Canada 2020 policy forum on Monday in Ottawa, Mr. Trudeau said that in addition to being less confrontational with Washington, he would implement several policy changes should his party form government in the fall.

He promised to push for a clean energy and environment agreement with Mexico and the United States that would involve the alignment of "climate mitigation policies" and international negotiating positions.

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The Liberals are also promising they would lift the visa requirement on Mexican visitors to Canada, which has been a source of irritation to Mexico's government. Mr. Trudeau said he would also create a cabinet committee on Canada-U.S. relations and work on improving border infrastructure.

The Conservative government responded by saying the three nations already have a working group on climate change and energy policies. The Tories said Canada has struck the right balance by reducing costly and unsuccessful refugee claims while planning to eliminate the need for Mexicans to reapply for a visa when re-entering Canada.

Foreign Affairs Minister Rob Nicholson said in a statement that Mr. Trudeau lacks foreign policy experience.

"At a time of global insecurity and economic volatility, Justin Trudeau is simply just not ready to lead," he said, repeating the slogan of Conservative ads that criticize the Liberal leader.

The focus of Mr. Trudeau's speech was largely to criticize Prime Minister Stephen Harper's tactics in the government's bid to have Washington approve the Keystone XL pipeline, which would bring Alberta crude to refineries on the Texas Gulf Coast.

Mr. Harper and his ministers have advocated for the project during visits to the United States. The Prime Minister said in New York in 2011 that U.S. approval should be a "complete no-brainer," and two years later in New York said Canada would not take no for an answer.

Mr. Trudeau – who also supports the Keystone project – said it would be more effective to improve Canadian environmental policies to help the project gain greater acceptance.

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According to the Liberal leader, the root of the problem is Mr. Harper's unwillingness to work with political leaders who do not share his ideology.

"The problem is not just Harper's antagonistic style of diplomacy," Mr. Trudeau said. "His hyper-partisan approach also means he is unable to work constructively with people who don't share his ideology, whether that person is President of the United States or Premier of Ontario."

Mr. Trudeau's speech concluded by stating: "The Harper d‎ecade has been defined by the absurd spectacle of a hectoring, belligerent Canada. It's time for it to come to an end."

The Liberal leader did not indicate what type of measures or targets should be in a North American climate change agreement. He said later he will deliver a "large speech" next week on the environment.

Carlo Dade, a director of the Canada West Foundation who specializes in North American trade relations, said Mr. Trudeau's speech reflects the opinion of many who monitor the relationship.

"If you talk to people privately in D.C. or in Mexico City, everyone's on the same page that the relationship's in trouble and they point to Canada as being the weak link," he said. "There's no sense that the government's engaged in trilateral [issues]."

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Mr. Dade said the visa issue is a major irritant, and Canada's planned new rules will not eliminate Mexico's objections.

"The reforms are still a very, very distant second-best," he said.

Canadian Chamber of Commerce president Perrin Beatty said he was glad Mr. Trudeau views the U.S. relationship as a priority. While he does not fault Mr. Harper's focus on the Keystone project, Mr. Beatty said his relationship with the President is not as effective as in the past.

"What is lacking is the type of mutual commitment that Brian Mulroney had with Ronald Reagan and George H. W. Bush, where they would spend political capital to resolve bilateral issues," he said.

Earlier this year, Canada surprised Mexico and the United States by postponing the annual Three Amigos gathering, which had been expected to take place in Canada in February.