WASHINGTON -- In his first foreign trip as leader of the official Opposition, Andrew Scheer avoided any criticism of the Liberal federal government, telling a Washington audience that Canada speaks with one voice on NAFTA.

The Conservative leader was at the Wilson Center on Wednesday explaining that he and Prime Minister Justin Trudeau have their partisan differences, but not when it comes to preserving the Canada-U.S. relationship.

"On NAFTA, the Canadian Parliament ... is united," Scheer told the think tank.

"We have our partisan differences. When we hold the government to account, as is our role in our parliamentary system, we will absolutely point out what we think they should be doing differently," he added. "But when it comes to our relationship with the United States we do speak with one voice.

"We want to make sure we're here to support our government's efforts in maintaining and protecting what we have in NAFTA. I believe it's important to send that signal to interests here in Washington."

He later avoided being pulled into the more controversial aspects of negotiations to renew the continental trade pact. One of the attendees of the event -- David Wilkins, a former U.S. ambassador to Canada -- asked him to suggest what concessions Canada and the U.S. should be prepared to make to get a deal.

Scheer replied: "I don't think it would be helpful."

Scheer is in Washington with several Conservative MPs for meetings with the U.S. transportation secretary, the U.S. Chamber of Commerce, former George W. Bush-era officials Robert Zoellick and Josh Bolton, and with some lawmakers on Capitol Hill.

It's his first working visit outside Canada in his new role.

The head of the Wilson Center, former nine-term Democratic congresswoman Jane Harman, contrasted Scheer's approach to NAFTA with the partisanship in Washington. She opined that the U.S. political model is broken, with politicians being rewarded by their primary voters for bashing the other party, and punished if they try working across the aisle to solve problems

"Your politics are more adult," she told Scheer.

To which the Conservative leader replied: "You haven't seen (our) question period."

Scheer said he's heard lots of anxiety from businesses in Canada, asking what he's hearing about NAFTA in Ottawa. He said he's now trying to learn more about the state of the negotiations from people in Washington.

The next round of negotiations is scheduled for next week in Montreal. While U.S. President Donald Trump has repeatedly threatened to start pulling out of the agreement as a negotiating ploy, lately he has made more positive comments about the negotiations.

Asked later if his visit had reassured him, Scheer said he had mixed feelings: he's more confident that many people are fighting to keep NAFTA from being cancelled but cancellation remains a possibility.

"(So) yes and no," Scheer said.

"I'm encouraged that there is a high level of engagement from people here in Washington -- both on the elected side and from people that represent industries. One of our concerns was, 'Will people here in the U.S. who support NAFTA become engaged and help make the case?' I've been very encouraged by that," he said.

"But at the same time it's also clear that they're doing so because they think the risk is real."