Canada's new ambassador to the United States said Thursday that resolving a decades-long lumber dispute with Washington would be his first priority, and he predicted a new tone in relations between the neighbors.

The Bush administration began imposing antidumping duties against Canadian lumber in 2002. Canadian lumber exporters have paid more than $4.3 billion in duties so far. Canada insists the tariffs are unfair.

The dispute has fueled talk of a trade war between the world's largest trading partners. Canada and the United States conduct some $1.6 billion in trade across their shared border each day.

Michael Wilson, confirmed Thursday as the new envoy to Washington, said sorting out the contentious issue starts at the top with the new prime minister, Stephen Harper.

Harper, elected Jan. 23, pledged during his election campaign that he would stand firm on Canada's position that the tariffs were unfair. But he also vowed to find a solution.

The World Trade Organization ruled Wednesday that Washington had complied with its international obligations in applying punitive antidumping duties against Canadian lumber imports.

Wilson, 68, brokered Canada's first free-trade agreement with the United States and Mexico, known as the North American Free Trade Agreement.

Wilson said Harper would set a new tone for the Canada-U.S. relationship, which suffered considerably under the two previous Liberal Party administrations of Paul Martin and Jean Chretien.

"I think the prime minister has indicated that he wants to see a change in the tone at the top," Wilson said. "He has started the dialogue with President Bush already in that regard."