The U.S. ambassador to Canada has hinted that Washington may try to convince the incoming Liberal government to maintain a combat mission against ISIS, even though prime minister-designate Justin Trudeau has vowed to end it.

"I don't actually want to presume an outcome here," Ambassador Bruce Heyman told CBC News chief correspondent Peter Mansbridge. "He hasn't formed his government, and we'd like the opportunity to come in and sit down with the government and talk about the broad aspect of the coalition and what we're trying to get accomplished."

Mansbridge asked Heyman if he was suggesting the U.S. would like the opportunity to lobby Ottawa to continue with the existing mission.

"What I'm really saying is I'd like the opportunity at every file with every minister to sit down and have a conversation," Heyman said. "Develop a relationship so that we can sit across the table and talk about opportunities. And where there are differences, have a good understanding for each other of where we see things differently and work to really good outcomes that work for both of us."

Canada has deployed CF-18s to take part in the U.S.-led coalition's airstrikes against ISIS. But Trudeau has said he wants to pull those fighters, provide more humanitarian aid in Iraq and Syria and have Canada's military involved in training missions, not bombing missions.

Trudeau, who spoke with U.S. President Barack Obama on Tuesday, said they discussed Canada's role in the mission and that the president "understands the commitments I have made around ending the combat mission."

U.S.-Canada differences 'small,' ambassador says

Heyman denied that relations between the U.S. and Canada have been damaged under Prime Minister Stephen Harper's watch. Some suggest a tense relationship has developed over the Keystone XL pipeline. Harper has lobbied the U.S. for years to approve the pipeline, calling the approval a "no-brainer" and that he "would not take no for an answer."

"I wouldn't use that term [damaged] at all," Heyman said. "In fact, I reflected back over the last couple of days on the U.S.-Canada relationship, and as I think about the U.S.-Canada relationship right now, there were a lot of successes, and we have to thank the prime minister for the work that he did on enhancing it."

Heyman said the U.S. and Canada are at record levels of trade and they had just signed the Trans-Pacific Partnership trade deal.

"I would say there are smaller differences on a few issues."

Mansbridge also asked Heyman about the suggestion by Wisconsin governor and former Republican presidential contender Scott Walker that he would consider putting up a wall at the Canada-U.S. border.

"That's absurd," he said. "That's just absurd."