The U.S. and 11 countries in the Pacific region last year reached an accord on the TPP deal to liberalize trade among the participating countries and set common standards and cut barriers. However, doubts have grown over the deal after leading presidential candidates in the U.S. adopted a more protectionist stance ahead of the elections in November.
"I think U.S. credibility goes almost to zero in the region if we don't get that done," said Christopher Johnson, senior adviser at Center for Strategic and International Studies in Washington DC.
"It really is the economic component of the US pivot to Asia. If we don't get this done in the lame duck-session in Congress--which now looks very likely since we have both major candidates opposing the deal--it really is a great advertisement for China message in the region," he told CNBC's "Squawk Box" on Friday.
China will be able to use the failure to pass to deal to say "look the US is about military and stirring up trouble in the region. We are about trade and growth and the failure of the TPP would demonstrate that," added Johnson who was previously a China analyst at the Central Intelligence Agency.
This would help the East Asian giant's international push, he added.
"For many years post-(former leader) Deng Xiaoping, the notion was keep a low profile internationally and focus on domestic development and growth. Since President Xi (Jinping) came into power, this idea of a more active Chinese foreign policy has come to the fore and we see that in the U.S.-China relationship as well," said Johnson.
Today's China however is unwilling to play second fiddle to the U.S. and Xi does not seem not "as solicitous of the U.S. relationship as his predecessors who put a lot of their energy or foreign policy bandwidth into managing that relationship," he added.
Regional countries have also leaned towards keeping peace with the world's second-largest economy, which has made significant investments in much of developing Asia.
The Asean-U.S. Summit in Laos last week was a case in point as Southeast Asian countries played down differences with China.
A statement from the meeting released Thursday mentioned that several countries were "seriously concerned over recent developments" in the South China Sea, Reuters reported.
The statement made no reference, however, to a July ruling by an arbitration tribunal in The Hague that rejected China's claims to economic rights across large swathes of the South China Sea.
"Clearly, there have been some differences between Asean countries who have largely decided to give China a pass on these activities, and the U.S. and Japan which are the only two countries calling China out," noted Johnson.