A bipartisan group of senators on Friday arrived in Ottawa seeking to stabilize the United States’ relationship with Canada, determined to mend a once-tight alliance that President Trump has tested in recent months with tariffs and tough talk.

Sporting lapel pins of the American and Canadian flags and red and white friendship bracelets, the group — four Democrats and a lone Republican — met with Prime Minister Mark Carney and senior Canadian officials in a bid to defuse the tension that has built up in recent months after economic pressure and political rhetoric from Mr. Trump that many Canadians have viewed as both destabilizing and deeply insulting.

“We know how important Canada is to our states and how important the United States and the Canadian relationship is to both countries,” said Senator Jeanne Shaheen of New Hampshire, the top Democrat on the Foreign Relations Committee, after a day of meetings with government officials and business leaders.

She was part of a delegation that included fellow Democratic Senators Tim Kaine of Virginia, Amy Klobuchar of Minnesota and Peter Welch of Vermont, as well as Senator Kevin Cramer of North Dakota, the sole Republican.

“We hope that this meeting will continue very positive discussions toward ensuring that some of the cracks that have appeared in the relationship in recent months are healed, and we move forward together,” Ms. Shaheen said.

Those cracks include Mr. Trump’s tariffs, which disrupted regional economies dependent on trade with Canada, as well as rhetoric that many Canadians found demeaning. The president’s repeated remarks suggesting that Canada should become America’s “51st state” and that the United States was being exploited by the relationship were initially dismissed as misunderstood humor or unorthodox negotiation tactics. Now, they are widely viewed in the country as disrespectful and damaging to Canadian sovereignty.