The White House says it can still win congressional approval of the Trans-Pacific Partnership trade pact before US President Barack Obama leaves office, and has warned failing to do so would undermine US leadership in the region.
"The president is going to make a strong case that we have made progress and there is a path for us to get this done before the president leaves office," White House spokesman Josh Earnest told a news briefing ahead of Mr Obama's trip to Asia this week.
Mr Obama has made the 12-nation free trade deal, which includes Australia and New Zealand, the centrepiece of a diplomatic "pivot" to Asia, but the prospects for congressional approval have looked increasingly dim, with both major presidential candidates - Democrat Hillary Clinton and Republican Donald Trump - standing opposed.
US Senate Majority Leader Mitch McConnell said on Thursday the Senate would not vote on the pact this year, punting it to the next president, who will take office in January.
The White House said on Monday that Mr Obama would make the case for the TPP during his visit to Asia, including in a speech he has scheduled in Laos on September 6.
Administration officials argue a failure to approve the trade pact would cede ground to China in the region and allow it to increasingly set the terms of world trade.
"It would be seen as a significant setback, I think, for American leadership if we don't move forward," Ben Rhodes, the White House deputy national security adviser, told the briefing.