Canada is leaning on the United States to help settle a dispute with China, which has started to block imports of vital Canadian commodities amid a dispute over a detained Huawei executive.
In a sign of increasing frustration at what it sees as a lacklustre US response, Prime Minister Justin Trudeau's government is signalling it could withhold cooperation on major issues.
China has upped the pressure on Canada in recent weeks over the arrest of Huawei Technologies Co Ltd Chief Financial Officer Meng Wanzhou, arrested last December on a US warrant. It halted Canadian canola imports and last week suspended the permits of two major pork producers.
After Meng's Vancouver arrest, Chinese police also detained two Canadian citizens.
Beijing is refusing to allow a Canadian trade delegation to visit, forcing officials to use video conference calls as they try to negate a major threat to commodity exports.
With no cards to play against China without risking significant economic damage, Canada has launched a full-court press in Washington, which is negotiating its own trade deal with Beijing.
The results have been meagre.
"It's a very challenging situation. When we raise it with the Americans they just say, 'Dealing with the Chinese is tough'," said a Canadian government source.
"It's also not clear who we should be targeting since you never know who is up and who is down in the administration at any given point," said the source, who requested anonymity given the sensitivity of the matter.
Among those the Canadians approached are Secretary of State Mike Pompeo, Agriculture Secretary Sonny Perdue, US Trade Representative Robert Lighthizer and Republican Senator Jim Risch, chairman of the Foreign Relations Committee.
The State Department said it was "concerned" by the canola ban. In March, the Foreign Relations Committee responded to Canada's concerns by passing a bipartisan resolution supporting the country.
Canada says the United States is obliged to help, given that the US arrest warrant triggered the crisis with Beijing.
US negotiators have rejected Chinese proposals to include the Huawei issue in their current trade deal discussions, according to a source familiar with the negotiations.
Canada's US ambassador David MacNaughton, who noted Canada has assisted the current US administration on diplomatic efforts with Venezuela, Latvia and Nato, strongly suggested future requests for aid would not be met so positively unless Washington cooperated more.
"How do you go to canola farmers and relatives of the two (Canadian detainees) and say 'Well, actually, notwithstanding all of this, we're going to try and do whatever we can to help?'" he said.