Malcolm Turnbull has met with the US Speaker Paul Ryan at his office on Capitol Hill, discussing the need for a major 12-nation trade pact.
The prime minister and the most senior Republican in Congress spoke of the threat of protectionism during their sit-down on Thursday afternoon (local time).
They agreed the Trans-Pacific Partnership would be a benefit to the region.
Speaker Ryan also agreed with Mr Turnbull's view that the deal was not just an economic issue, it was a statement of the US's engagement with the region.
The Speaker last month queried the point of validating the TPP in what is regarded as a lame duck period for US political leaders between the November presidential and congressional elections and January's inauguration.
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"As long as we don't have the votes, I see no point in bringing up an agreement only to defeat it," he is reported to have said in an interview with Wisconsin Public Radio.
Mr Turnbull earlier in the week said President Barack Obama was optimistic the agreement could be approved during the lame duck period.
Earlier this week, ahead of a meeting with Mr Turnbull, former New York mayor Michael Bloomberg said there was no more important legislation to the US than the TPP.
