Malcolm Turnbull says it's Barack Obama's challenge to find a solution to US legislative hurdles on a 12-nation Pacific trade pact.
The prime minister says the US appears to be the source of the strongest domestic concerns to the Trans-Pacific Partnership agreement.
"That seems to be the major domestic hurdle ... of the 12 nations," he told reporters in Manila on the sidelines of the Asia-Pacific Economic Cooperation summit.
"That's President Obama's challenge."
Mr Turnbull's comments were made shortly before he held a meeting with 11 other leaders of nations involved in the pact, the first since it was agreed to.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The group discussed ways to ensure the agreement was enacted in each respective country, while also noting a number of other APEC member nations not part of the deal were seeking a place. They include Indonesia and the Philippines.
"This interest affirms that through TPP we are creating a new and compelling model for trade in one of the world's fastest growing and most dynamic regions," the leaders said in a joint statement.
Mr Obama, who hosted the meeting, acknowledged during the meeting the politics of any trade agreement would be difficult.
The TPP is facing stiff opposition from many Democrats and unexpected resistance from Republicans.
Mr Turnbull urged legislators in Washington to support the pact.
"But I imagine they would be taking the advice of their own constituents rather than foreign governments," he said.
