The chances of a final agreement on a Pacific trade pact being reached have been put at 50/50.
Australian Trade Minister Andrew Robb remains in back-to-back meetings in the US on the 12-nation Trans-Pacific Partnership deal, with biologic drugs still the main sticking point.
It's understood Australia has made some progress on market access for agriculture and seafood, with those on the ground putting chances of an imminent conclusion at 50/50.
Opposition leader Bill Shorten said the federal government must assess whether it's in Australia's national interest to sign up to the trade pact.
"Our concern is that if we do a deal with America we make our medicines more expensive," he told reporters in Sydney.
"If that's the case we would be less enthusiastic about the deal."
Mr Shorten is hoping the US will give some ground on drug patents.