After boycotting American products and shunning vacations south of the border, Canadians in their thousands are pouring their incandescent anger at the United States into a new cause: ousting the American ambassador.

More than 170,000 people have signed a petition to the Canadian Parliament, submitted by a Calgary resident on July 21, calling for the removal of the ambassador, Pete Hoekstra.

The petition asserts that Mr. Hoekstra, a faithful messenger of President Trump’s aggressive stance toward Canada, has harmed U.S.-Canada relations. The two countries are locked in a trade war, and their relationship, once the closest two nations can be, has been at a historic low since Mr. Trump retook office.

Just 500 signatures are legally required to bring an online petition to the Parliament floor for discussion, and this one will most likely be put forward for debate in the fall by Elizabeth May, the leader of Canada’s Green Party.

The petition lays out the reasoning for Mr. Hoekstra’s removal: it argues that he has “normalized the Trump administration’s threats to annex Canada as the 51st state.” Mr. Hoekstra has reposted Mr. Trump’s 51st-state jabs on social media and has dismissed Canadians’ anger at the rhetoric as “emotional” and inexplicable.

It also states that Mr. Hoekstra has interfered in Canadian politics in a manner “inconsistent with diplomatic protocol.” It lays out how activists from Alberta seeking to break away from the rest of the country repeatedly met with State Department officials, “raising serious questions about U.S. diplomatic interference in Canadian unity.”

The petition calls on the Canadian government to invoke the Vienna Convention of Diplomatic Relations, the international accord that governs diplomacy, declare Mr. Hoekstra “persona non grata” and request his removal from office, as well as to set up a parliamentary committee to review “U.S. diplomatic interference in Canadian domestic affairs.”

The United States Embassy in Ottawa referred questions to the State Department, which did not respond to a request for comment.

The petition culminates months of souring public sentiment toward Mr. Hoekstra personally, mirroring the plummeting views toward the United States generally.

Polling shows Canadians’ opinion of the United States has rapidly gotten worse since Mr. Trump took office and began targeting Canada with tariffs and talk of making it part of the United States. A Pew survey published in June found that only 35 percent of Canadians now view the United States as a reliable partner, down sharply from 2022, when it was 82 percent. Canadian recreational visits to the United States have shrunk by more than a quarter over the past year.

In this context, Mr. Hoekstra, a former Republican Representative from Michigan, has become notorious in Canada for his blunt, unapologetic tone, which channels Mr. Trump’s.

One comment that drew ire came in November, when Mr. Hoekstra was asked if he understood why Canadians found Mr. Trump’s 51st state remarks upsetting.

“Here, I’ll just get myself in trouble,” he said. “I go around the country and people will say, ‘Pete, you just don’t understand why we’re so mad about the 51st state.’ Yeah, you’re right. I don’t.”

Unlike some of his colleagues, Mr. Hoekstra has never been summoned by the Canadian government, a step taken when a diplomatic emissary is seen as overstepping so badly that the host government needs to give them a talking-to.

The United States ambassador to France, Charles Kushner, the father of Mr. Trump’s son-in-law, Jared, has been twice summoned by the French government over comments he has made about French domestic affairs. The U.S. ambassador to Belgium was also summoned for comments he made.

Mr. Hoekstra also raised eyebrows when he invited the right-wing populist activist Tamara Lich, who had been convicted of organizing the trucker convoy that wreaked havoc in Ottawa for a month in 2022, to this year’s 4th of July party at the ambassador’s official residence.

Mr. Hoekstra has been accused of political interference in another nation’s domestic affairs. In 2020, while serving as U.S. ambassador to the Netherlands in the first Trump administration, he hosted an event at the U.S. embassy with a nativist, anti-immigrant Dutch party.

Expelling a U.S. ambassador would be a first for Canada, but far from unprecedented globally.

American ambassadors have been expelled during major geopolitical crises in the past, including during the Cold War, both World Wars, as well as more recently during crises with Latin American countries such as Venezuela.

Mr. Hoekstra’s stance in Canada aligns with the U.S. administration’s foreign policy elsewhere. The State Department has made significant efforts to cultivate and promote identarian politics in Europe through visits and senior official meetings with European political parties and other organizations sharing these ideas, including in Germany and Britain.

Representatives of the business community said Mr. Hoekstra had been a solid interlocutor during tumultuous times for the relationship between the two nations.

The U.S. Embassy in Canada recommended speaking to some business leaders about their working relationship with Mr. Hoekstra. They included Rick Tachuk, president of the American Chamber of Commerce in Canada, a private, nonprofit membership organization promoting trade and investment across the border; and Beth Burke, chief executive of the Canadian American Business Council, a nonprofit, nonpartisan group.

Mr. Tachuk says that Mr. Hoekstra has been available to business leaders and cares about the U.S.-Canada trade relationship.

“He at times can be blunt, but, in many respects, that is an advantage for us because he helps articulate the view of the president, and helps us understand what the challenges are,” Mr. Tachuk said in an interview on Friday.

“Ambassador Hoekstra has to deliver some very unpopular messages here in Canada. It’s a tough job but he’s doing his best,” he added.

Ms. Burke said Mr. Hoekstra was well connected across the administration and an effective messenger.

“I also really value knowing where you stand in a situation. Sometimes pleasantries and diplomatic speak muddy the waters,” she added.