Trade experts said the administration comments pointed to a long phase-out period for tariffs Japan was prepared to move on such as beef, which it agreed to cut in a deal with Australia weeks earlier, while allowing continued protection for sectors such as rice.
"That's something that the United States can do, because U.S. negotiators are not under extreme political pressure to get a comprehensive reform on rice," said Peterson Institute for International Economics trade analyst Jeffrey Schott.
Officials from other TPP countries noted U.S. recognition of the role market access played in persuading other TPP partners to sign up to common rules on issues such as intellectual property, important to the United States and Japan.
For big agricultural exporters such as Canada, New Zealand and Australia, access to Japan's markets might offset doubts about the intellectual property rules.
"Once it's clear that there is going to be a U.S.-Japan deal that is perceived to be a good deal for everybody ... there will be decisions made," the aide said. "There will be trade-offs, trade-offs not just in the market access talks but trade-offs within the rules package as well, across the entire agreement."
The joint statement also called on other trading partners to take steps needed to conclude the agreement, making clear the United States and Japan do not want to bear the burden alone.
"It's going to take all 12 countries, not two, in order for TPP to cross the finish line," said Alston & Bird policy adviser Eric Shimp, a former U.S. Trade Representative negotiator.
But Japan would likely have to go into more detail about its concessions to prompt Canada to open up its dairy and poultry markets.
"It's hard for me to see Canada offering more market access, or showing its hand, before Japan does. The sequence is fairly clear," said McDermott Will & Emery partner Jay Eizenstat, also a former USTR negotiator.