Malaysia's Prime Minister Najib Razak says his government will have to discuss the Trans-Pacific Partnership (TPP) in Parliament to get domestic buy-in for the ambitious free trade deal, even as the United States says it hopes to conclude negotiations by December.
"The TPP is more than a normal trade agreement," he told a panel discussion at the Asia-Pacific Economic Cooperation (Apec) CEO Summit on Monday.
He added: "Once you go beyond that and into areas of intellectual property, investor-state dispute settlement, state-owned enterprises, the environment and labour - you impinge on fundamentally, the sovereign right of the country to make regulations, policies.
"That is the tricky part - and that is why we asked for flexibility."
Several of the proposals under the TPP, a pan-Pacific trade pact under discussion between 12 nations, have been met with opposition in Malaysia on the grounds that they infringe on the country's sovereighty and independence.
US commerce secretary Penny Pritzker told reporters on Sunday that Washington remained focused on reaching a deal on the ambitious pact by year-end.
Mr Najib said that was the desired timeline, but noted that it was "not cast in stone".
The TPP seeks to group the economies of the United States, Australia, New Zealand, Japan, Singapore, Malaysia, Brunei, Vietnam, Chile, Canada, Mexico and Peru in what has been described as a "gold standard" free trade agreement. All are among Apec's 21 member economies.
President Barack Obama was due to chair a meeting of leaders of the 12 participating countries here on Tuesday. But the ongoing US government shutdown prompted him to cancel the meeting as well as his long-planned trip to Southeast Asia.
New Zealand Prime Minister John Key will now chair that meeting.
On Monday, Mexican president Enrique Pena Nieto - who shared the stage with Mr Najib - said he was also determined to close the deal this year.
"But it is about being flexible in terms of the negotiations," he said. "It is our aim - and it is up to the will of member countries - to reach a solution as soon as possible."