US President Donald Trump has agreed to reconsider the Trans-Pacific Partnership (TPP), a free trade pact with primarily Asia-Pacific countries that he backed out of last year.
Mr Trump made the commitment while meeting politicians from farming states, who are among those concerned about a trade war, senators say.
The president has previously slammed the deal as a potential "disaster".
But his trade strategy is under fire as a conflict escalates with China.
Politicians, including some from his own party, are worried that he is leading the US into a damaging economic battle with China, after levying tariffs on steel and aluminium and threatening taxes on billions more in Chinese goods.
They have said the administration should be working with other countries to pressure China, instead of wielding tariffs that invite retaliation on industries such as agriculture.
Senator Ben Sasse, a Republican who represents Nebraska and has been sharply critical of the tariffs, said it was "good news" that the president directed top staff, including US Trade Representative Robert Lighthizer, to negotiate US entry into TPP".
"The best thing the United States can do to push back against Chinese cheating now is to lead the other 11 Pacific nations that believe in free trade and the rule of law, " he said.
The TPP, a trade deal that was to involve 12 countries including the US, was conceived under former President Barack Obama as a way to counter China's surging power in the region.
Labour unions and others had criticised it as too favourable to business. Mr Trump's Democratic rival in the 2016 election, Hillary Clinton, also came out against the agreement during the campaign.
Withdrawing from the deal was one of Mr Trump's first acts as president, delivering one of his core campaign promises.
After he withdrew, the remaining 11 countries continued to negotiate over the pact, signing the deal in March.
Exporters, such as farmers, have said they are now concerned that the US will be at a disadvantage to competitors in the region.
Mr Trump ordered his staff to evaluate rejoining "on our terms", according to accounts from the meeting. He has previously said he might reconsider the deal.