US Secretary of State John Kerry has warned of grave consequences for America if the nation walks away from the Trans-Pacific Partnership (TPP).
In a passionate 40-minute speech in Washington DC on Wednesday, Mr Kerry said not only would the US economy suffer and relationships with close allies like Australia, New Zealand and Japan be hurt, the sinking of the TPP would lessen America's influence on combatting North Korea's nuclear program and China's territorial claims in the South China Sea.
Commanders "of every army and navy" in the region will notice in a way "that does not work for the United States of America".
"If we reject TPP we take a giant step backward," Mr Kerry said at the Woodrow Wilson Center for International Scholars.
Asia-Pacific nations, instead of looking to the US for leadership, would look elsewhere.
"It will be a unilateral ceding of American political influence and power with grave consequences for the long term," he warned.
"And I've got news for you.
"They're going to be asking themselves, 'Hey, if we can't count on the US where else should we turn?'"
The US presidential election has turned the TPP into a toxic issue, with frontrunners Hillary Clinton and Donald Trump opposing the 12-nation trade pact.
US President Barack Obama is determined to push the TPP through Congress before he leaves in office in January, but in the lead-up to the November 8 presidential and congressional elections candidates are wary of showing support for the unpopular trade deal.
The TPP pact would be between the US, Australia, Japan, New Zealand, Canada, Mexico, Chile, Singapore, Malaysia, Brunei, Vietnam and Peru.
"Our presence, our influence in the Asia-Pacific is essential for the protection of our own interests and believe me, that presence is welcome and highly valued by friends in Asia," Mr Kerry said.