This story has grown to be more than the regular Trump lies we see on a daily basis.

On Thursday, Trump repeated his false claim that the United States runs a trade deficit with Canada. This was the morning after privately telling Republican donors that he had deliberately insisted on that claim in a meeting with Prime Minister Justin Trudeau of Canada even without knowing whether it was true or not.

Trump’s private admission to having a loose grasp of the facts and his public refusal to back down from the lie — the United States has an overall surplus in trade with Canada — were vivid illustrations of the president’s cavalier attitude about the truth, and a reminder of how that approach has taken hold at the White House.

Sarah Huckabee Sanders, the White House press secretary, said Trump had chosen his figures “selectively” in the conversation with Trudeau.

She also acknowledged that Trump had fabricated an anecdote he told the donors about unfair trading practices — Japanese officials, he claimed, conduct a test on American cars by dropping a bowling ball on their hoods from 20 feet high, and those that dent are barred from being imported. That is completely not true.

Marc Garneau, who is the chairman of the Canada-U.S. relations committee in Trudeau’s cabinet, rejected on Thursday the president’s deficit claim.

“At this point, it’s very important to point out that there is over $2 billion a day of trade between our two countries and over all annually the United States has a small surplus with Canada,” Mr. Garneau told reporters in Montreal.

The president’s reported remarks dominated the news in Canada on Thursday morning and were greeted with bafflement.

“It is scary, as his lying has become the new normal,” said Cory Whiteduck, 35, a radio host and cigarette seller in Kitigan Zibi reserve, near Maniwaki, Quebec, about 85 miles north of Ottawa. “Normally, it would raise red flags, and a politician would be in trouble. It is not a productive way of doing things or a good mentality.”

Bruce A. Heyman, the United States ambassador to Canada under President Barack Obama, said that Mr. Trump’s approach was “creating a crisis where none existed before.”

“Lying to your friends only hurts the relationship,” Mr. Heyman wrote on Twitter. “Canada has been there for us thru thick and thin. How can you just casually damage this realtionship?”