U.S. trade officials left Japan yesterday after two days of talks with major disputes still remaining for the two countries to resolve before they and 10 other countries can conclude the broader Trans-Pacific Partnership (TPP) free trade agreement.

Top trade officials from Japan and the United States met this week in Tokyo for discussions focused largely on the U.S. push for Japan to drop its steep tariffs on agricultural products and on automotive barriers between the countries. Japan wants to protect nearly 600 products in five agricultural categories–meat, rice, sugar, diary, and wheat–from tariff elimination under the pact.

“Our teams arrived expecting that the talks would be tough, and our expectations have been met,” U.S. Trade Representative Michael Froman said to reporters before returning to Washington. “We’ve made some progress over the last two days, but there are still considerable differences in our positions on key issues,” he said.

“We understand the challenges–these negotiations relate to fundamental reforms in the market opening of sectors in Japan that have traditionally been closed. But let’s keep in mind the TPP offers enormous opportunities for both Japan and the United States,” Ambassador Froman said.

Former U.S. trade negotiator Craig Thorn, and now a partner at the agricultural policy firm DTB Associates, said at a Washington International Trade Association discussion yesterday that a deal eliminated most of Japan’s tariffs on agricultural products is still possible, but that it would probably require months of additional pressure from the United States.  “I think this market access negotiations can only be rushed to a certain extent.  It will probably take another few months for the process to unfold,” Thorn said, adding that he saw evidence that the Japanese government has put itself in a position to make the necessary agriculture reforms and accept trade liberalization, despite its public posture in the talks.

The state of current negotiations indicates there is little chance that President Barack Obama and Japanese Prime Minister Shinzo Abe will announce a concluded deal when Obama travels to Japan on April 24-25.

Japan’s stance is prompting some in Congress to call for the United States and the other TPP partners to push for a final agreement without Tokyo.   Japan knew eliminated tariffs was a goal of the TPP when it joined the four-year-old negotiations in 2013, but now it is asking other countries “to compromise a core principle of TPP that would quickly undermine the ambition and benefits,” said Tam Overby, vice president for Asia at the U.S. Chamber of Congress.

Earlier this week, Australia, one of the TPP countries, struck a bilateral trade deal with Japan that allows continued high tariffs on dairy and beef and excludes other agricultural products from tariff cuts, prompting U.S. farm groups to demand that the White House not agree to similar terms with Japan.