Rejoining the pact could be a significant change in fortune for many American industries that stood to benefit from the trade accord and for Republican lawmakers who supported it. The deal, which was negotiated by the Obama administration, was largely intended as a tool to prod China into making the type of economic changes that the United States and others have long wanted. Many economists say the best way to combat a rising China and pressure it to open its market is through multilateral trade deals like the Trans-Pacific Partnership, which create favorable trading terms for participants.

“The idea was to set a framework that eventually China would have to accommodate,” said David Autor, an economist at M.I.T.

Farmers would stand to benefit from new access to markets, especially Japan, if Mr. Trump rejoins the pact. For instance, ranchers in Australia can currently send beef to Japan more cheaply than ranchers in the United States.

Michael Miller, the chairman of U.S. Wheat Associates and a farmer in Washington, said rejoining the deal would allow his industry to compete on a level playing field with competitors in Australia and Canada, which both remained in the accord.

But rejoining it could be a complex task. The remaining countries, like Japan, moved ahead without the United States, and spent months renegotiating a pact before finally agreeing to a sweeping multinational deal this year. Mr. Trump, who has demanded that any such deal benefit the United States, is unlikely to rejoin the Trans-Pacific Partnership without further concessions for what he has criticized as a terrible agreement. That could complicate talks, since Japan maintains that it has already given all the concessions it could, said William A. Reinsch, a trade expert at the Center for Strategic and International Studies.

Yoshihide Suga, Japan’s chief cabinet secretary, on Friday cautioned against any efforts to change the agreement to accommodate Mr. Trump, calling it a “well-balanced pact” that addressed the needs of the 11 nations that signed the deal.