Last Friday in Tokyo, Prime Minister Shinzo Abe announced that Japan would join the negotiations, calling it a "last chance" for his country to help craft new regional trade rules. The bid by the world's No 3 economic power is subject to approval by the 11 current TPP negotiators.

"For Japan, to remain inward-looking means we are giving up on the possibility of growth," said Abe, whose decision came amid tension within his pro-business Liberal Democratic Party, including fears that the TPP could harm Japanese farmers.

The US, Marantis said, welcomed Japan's move.

On Friday, his first day as President Barack Obama's point man on trade, he said "important work remains to be done" to resolve issues over Japanese policies in the automotive and insurance sectors.

US Representative Ed Royce, who is chairman of the House Foreign Affairs Committee and has voted in favor of most free trade pacts during his time in Congress, supports the TPP, but believes it won't be enough to restore US economic influence in the region.

"The center of economic activity within Asia has shifted gradually away from the US to China," the California Republican said on Wednesday in a speech at the Heritage Foundation, a conservative think tank, in Washington.

"Intra-regional trade between China and Southeast Asia has grown tremendously. Trade between China and Australia has also grown. Even Japan is now more focused on the Chinese market than the American market. And while I fully support Japan's expressed interest to join the Trans-Pacific Partnership free trade agreement, the TPP alone cannot reverse this trend."

Jon Tayor, a political science professor at the University of St Thomas in Houston, said that while the current trajectory of US-China relations is positive, given China's new leadership and Obama's nascent second term, the TPP can be seen as a symbol of lingering mistrust.

"Treating China like an opponent by not including it in the Trans-Pacific Partnership is counterproductive at best," Taylor said. "It would be much more productive to recognize and nurture the symbiotic relationship between the world's two largest economies."

Marantis said at Wednesday's briefing that Washington is focused on discussions with Beijing to address "competitive distortions" to trade that State-owned enterprises, or SOEs, can create. He said such concerns are also being addressed within the TPP framework and on a recently announced trans-Atlantic trade agreement between the US and the European Union.

The Obama administration official, who succeeds Ron Kirk as trade representative, also pointed to negotiations with China on a bilateral investment treaty.

"It's very important. I think it will help really put important obligations in place that will create stability in the investment climate and address, I think, very important market-access issues as well," Marantis said.

Contact the writers at josephboris@chinadailyusa.com and lijiabao@chinadaily.com.cn