In April, the White House formally notified Congress that it intended to include Japan, the world's third-largest economy, in negotiations as part of the Trans-Pacific Partnership (TPP).
"The objective of this negotiation is to achieve a high-standard, 21st century agreement with a membership and coverage that provides economically significant market access opportunities for America’s workers, manufacturers, service suppliers, farmers, ranchers, and small businesses," the USTR says in the notice.
"The addition of Japan to the group of TPP negotiating partners will contribute meaningfully to the achievement of these goals."
Members want to conclude negotiations in time for an October summit in Indonesia, though some analysts worry about the tight deadline.
There has been opposition to Japan's entry into the trade deal from manufacturing, agriculture and auto sectors.
The United Steelworkers have called Japan's participation "very troubling," and the UAW warned that without significant reforms, "Japan’s inclusion in the TPP will cost American jobs, undermine the business case for automotive investment and will not produce realistic opportunities for automotive exports to Japan."
The USTR is accepting input through June 9 and holding a public hearing on July 2.