Prime Minister Justin Trudeau made a personalized pitch to his American "friends" in Rhode Island Friday, urging U.S. governors to stand with Canada ahead of NAFTA renegotiation talks for the sake of economies on both sides of the border.

In his 20-minute address to some 35 U.S. governors, followed by a question-and-answer session, Trudeau urged Americans to avoid the populist appeal of protectionism and took a thinly veiled swipe at the "America First" rhetoric some U.S. leaders, including U.S. President Donald Trump, have used.

"Such policies kill growth. And that hurts the very workers these measures are nominally intended to protect. And once we travel down that road, it can quickly become a cycle of tit for tat, a race to the bottom, where all sides lose," Trudeau said.

"My friends, Canada doesn't want to go there. If anything, we'd like a thinner border for trade, not a thicker one," he said.

Formal talks on NAFTA could start as soon as next month, after the U.S. signals Monday which parts of the deal it hopes to revisit. Trudeau said he wasn't sure of the exact date — or location — of the first renegotiation talks, but that the government is planning for a mid-August start. U.S. media reports have suggested the first round will be held in the Rust Belt city of Pittsburgh.

Trudeau's aggressive American outreach seems to have already produced results. The prime minister said Friday, after his address to governors, that Trump told him Canadian steel and aluminum exports will likely not face a national security review.

"I have heard directly from President Trump as well that he does not think that Canada should be subject to national security concerns around the trade of steel and aluminum," Trudeau told reporters at a news conference.

"We continue to remain extremely optimistic that this important trade, which leads to millions of good jobs on both sides of the border, will continue in the best interests of both of our countries," he said.

The comments went a step further than what Trudeau said last weekend when asked about steel. He said then that he was "comfortable" the U.S. would exempt Canadian exports from such a review given the integrated nature of the North American steel market, and close defence ties that depend on these raw materials.

In April, Trump signed a presidential memorandum directing his Department of Commerce to investigate the national security implications of importing foreign-made steel. Canada accounted for 17 per cent of all steel imported into the U.S. last year.

Canada-U.S. relationship 'solid'

Trudeau continued his American lobbying efforts in Rhode Island with an appeal to governors to not lose sight of Canada, even if trade relations are typically the domain of the federal government.

"The truth about good neighbours is sometimes we take each other for granted.… My friends, we in Canada have decided we would not allow that to happen to our relationship."

He suggested states should not be content to cede trade talks to the federal government alone.

Trudeau defends cross border trade to US Governors1:52

Trudeau said he is asking governors to stand with Canada not just in the name of goodwill, but because it is in their self-interest to keep relations strong. He said some nine million U.S. jobs depend directly on trade between Canada and the U.S., while Canada is the largest export market for 35 states.

"To boil this down to one point: Canada is the U.S.'s biggest, best customer — by far," he said. In his closing news conference, Trudeau vowed to get the best deal "for all North Americans."

From Canada's perspective, the relationship is "solid, through and through," he said, speaking to the close military co-operation with Norad on the home front and to cultural ties such as the Broadway hit musical Come From Away, which tells the story of Newfoundlanders sheltering Americans in the aftermath of Sept. 11, and to the staggering amount of property taxes Canadians pay in Florida alone ($500 million a year).

But the Liberal leader also signalled an openness to make tweaks to some parts of the decades-old trade deal.

Trump and NAFTA

"NAFTA isn't perfect. No such agreement ever is. We think it should be updated and modernized, as it has been a dozen times over the past quarter century. And I have every expectation that it will be — to the ultimate benefit of working people in all three partner countries," Trudeau said, without specifying which areas he was opening to amending.

"We must get this right. Sometimes getting it right means refusing to take the politically tempting shortcuts," he said.

Trudeau's visit is part of a strategy to focus not only on politicians in Washington, who will ultimately decide the fate of NAFTA, but also to make inroads with other levels of government.

Trudeau and Kentucky Governor talk trade1:54

Trudeau did get public assurances from some powerful Republican politicians that NAFTA will be preserved.

Those reassurances didn't just come from the state governors but from Trump's vice-president. In his own speech to dozens of state governors, Mike Pence promised a collaborative approach.

"We will modernize NAFTA for the 21st century so that it is a win-win-win for all of our trading partners in North America," Pence said, as Trudeau clapped and Foreign Affairs Minister Chrystia Freeland took notes throughout the speech.

"Let me assure you, the United States and Canada have already built a remarkably strong relationship under these two leaders.… We're grateful for the prime minister's leadership and his early outreach to this administration. President Trump recognizes that every trade relationship can improve and … we're looking forward to bringing NAFTA into the future in a way that will equally benefit both our countries," Pence added.

Governor will stand with Canada '100%'

Ahead of the speech, Trudeau held a series of bilateral meetings with several governors, including leaders from Kentucky, Wisconsin, Rhode Island and Iowa.

CBC News spoke to a number of those U.S. governors, and most reaffirmed their support for continued trade relations with their neighbour to the north.

Kentucky Gov. Matt Bevin, a strong Trump supporter, sought to reassure Canadians Thursday. He said the president's tough talk is simply one of his negotiation tactics, and what he really wants is a renewed deal that is fair to all sides.

Trudeau sells NAFTA to U.S. governors | Sunday Scrum10:30

"That's how businesspeople do business, and he's not kidding. Canada should not expect a better deal than America," Bevin said in an interview with CBC. 

"But what he's really saying is that it needs to be updated, and it does. He's not saying we're going to get rid of it in its entirety. He's created, however, a dialogue that has forced people to the table and that's healthy."

New Hampshire Gov. Chris Sununu, a Republican, said he will stand with Canada "100 per cent" if talks go sour. It is not just out of consideration for close Canadian ties but also self-interest.

Trudeau, Pence

Prime Minister Justin Trudeau and U.S. Vice-President Mike Pence are scheduled to hold bilateral talks with governors. Pence and Trudeau delivered the keynote speechs at the meeting Friday. (Canadian Press/Associated Press)

With files from Peter Zimonjic and The Canadian Press