Four of the countries negotiating the Trans-Pacific Partnership initiative are offering the other members total tariff elimination on all agricultural and industrial goods, a source close to the talks said.

The move by Australia, New Zealand, Singapore and Chile is likely to put pressure on Japan, the second-largest of the 12 TPP economies, to open up its politically sensitive agricultural market, the source said Friday.

The other members of the free trade talks were expected to reveal their offers later Saturday, the fourth and final day of the lead negotiators’ meeting in Washington, the source said.

This could see Tokyo and Washington, which have only conducted bilateral negotiations since Japan’s belated entry into the TPP talks in July, join the multilateral-level tariff negotiations Saturday.

The chief negotiators from the 12 Pacific Rim countries are preparing for a special leaders’ summit on the U.S.-led pact next month in Bali, Indonesia, and want to strike a deal by the end of the year.

“The Washington meeting will try to close chapters that are easier to resolve. After that, deadlines will be given for chapters such as market access or rules of origin,” said an official from one of the TPP countries.

Another official said the lead negotiators dealt mainly with a dispute settlement mechanism on the first day and with labor issues on the second.

The 12 TPP members hope to forge at least a basic accord during the Bali summit for creating what would be one of the world’s largest free trade zones, accounting for around a third of global trade.

The chief negotiators’ meeting has run in parallel with a working group session on “market access,” which basically discussed tariff elimination for goods.

For Japan, which joined the talks in late July but didn’t take part in the tariff negotiations until last month’s round in Brunei, the sessions in Washington were expected to provide further chances for Tokyo to retain tariffs on sensitive farm products, Japanese officials said.

Tokyo is facing strong domestic pressure to protect sugar, rice, wheat, beef and pork, dairy and other farm products because farmers fear that an influx of cheap imports will devastate the nation’s agricultural sector.

Japan has exchanged lists of tariff-elimination items with Brunei, New Zealand, Malaysia, Mexico, Peru and Singapore so far, but the percentage of tariff-free items on its list remains relatively low at around 80 percent.

The goal of the TPP accord, in theory, is to get rid of all tariffs.