Trade ministers huddling on the sidelines of the Asia-Pacific Economic Cooperation talks in Hanoi, Vietnam, are faced with some tough challenges in resurrecting the TPP trade deal since U.S. President Donald Trump ditched it.

Aside from steering countries away from competing trade pacts, the architects of the Trans-Pacific Partnership must make it viable for the remaining 11 members while keeping a door open to a future re-entry of the U.S., which accounted for 60 percent of the group's total gross domestic product (GDP).

That's a tall order, but Hanoi is set to provide a platform for the 11 to huddle up and possibly come up with Plan B. "The TPP is clearly diminished with the U.S. out, but they will try and resurrect it," said Arup Raha, Chief Economist at CIMB.

In an exclusive interview with CNBC, Japanese Prime Minister Shinzo Abe said his country wants to the U.S. to return to the deal, but said the remaining members should stay united and not waste years of efforts.

"We have finally come to an agreement on the rules of free and fair trade," he said. "Since we have come thus far, Japan must now take on a leadership role and bring the talks forward."

Abe followed up those words with some action this week, when he met in Tokyo with the Prime Minister Bill English of New Zealand.

Both nations have ratified the trade agreement, and English said both countries "can and will" take a leading role in getting the trade pact back on track.

Though Japan appears to want to take point on the TPP, Tokyo will have to tread carefully given the delicate political balance in the region.

"For Japan, this is a political move to neutralize China," said George Yeo, a former Singaporean trade and foreign minister. A free trade agreement between the U.S. and Japan lay at "the heart of TPP," Yeo said. "Without the U.S., it is hard for Japan to give concessions on agriculture."