Trump economic adviser Larry Kudlow says a White House official called Canadian Prime Minister Justin Trudeau a "little punk kid running Canada."

In remarks Wednesday night at a dinner hosted by the conservative American Spectator magazine on Capitol Hill, Kudlow boasted about the Trump administration’s governance of the economy, saying that President Trump has ended the “war on business” and ushered in an economic boom. He defended the administration’s efforts to overhaul taxes and reduce regulations, as well as Trump’s efforts to overhaul trade deals.

Kudlow said that Trump’s aggressive stance in negotiations with China is justified, and also boasted about the U.S.-Mexico-Canada Agreement.

[Opinion: Trump's unpredictability sometimes gets results from the likes of Canada and Mexico]

“A friend of mine in the White House, who will go unnamed, said, 'You know, I know why you’re supporting this deal Larry, it’s because we made a deal. We didn't walk away, we didn’t end it, we made a deal. Alright? 'Spite that little punk kid running Canada, we still made it,’” Kudlow said, referring to Trudeau. “And I’ve had some wonderful run-ins with him.”

The alleged swipe at Trudeau by one of Kudlow's colleagues would be an extension of Trump's strained relationship with his Canadian counterpart, which took a turn for worse this year during trade negotiations.

During a fundraising speech in March, of which the Washington Post obtained audio and published the remarks, the president boasted of telling Trudeau that the U.S. had a trade deficit with Canada, even though he admitted he had no idea if it were true.

“I said, ‘Wrong, Justin,'" Trump said. "I didn’t even know. ... I had no idea. I just said, ‘You’re wrong.’ You know why? Because we’re so stupid. … And I thought they were smart. I said, ‘You’re wrong, Justin,'" Trump said, adding that he had his staff check. "Check, because I can’t believe it," Trump said, after which an aide told him the U.S. runs a surplus with Canada.

Over the summer, Trump accused the Canadian leader of acting “meek and mild” during their meetings in Quebec during the G-7 summit and being “dishonest” in the way he portrayed the newly imposed U.S. tariffs. He also claimed to have informed U.S. officials not to affirm a communique signed by G-7 members.

Following Trump's departure from the G-7 for Singapore, Trudeau held a press conference stating that all of the member nations, including the U.S., had signed a communique dedicated to lowering tariffs and other trade barriers. He also said in response to Trump's tweets, "We are focused on everything we accomplished here at the summit. The Prime Minister said nothing he hasn’t said before — both in public, and in private conversations with the President."

In recent months, the Trump administration signaled it would bail on the North American Free Trade Agreement, prompting talks with Mexico and Canada for a new deal. Amid the trade feud, Trump claimed in September that he refused to meet with Trudeau at the United Nations in New York. Canada denied that it had ever requested a meeting.

In expressing his dismay with negotiations, Trump appeared to take a shot at Canadian Foreign Minister Chrystia Freeland when he told reporters, "We’re very unhappy with the negotiations and the negotiation style of Canada. We don’t like their representative very much."

Despite the bad blood, the U.S. and Canada reached an agreement in late September to replace the three-nation framework of NAFTA with a new deal called the U.S.-Mexico-Canada Agreement.