Chief negotiators for a Pacific trade deal will meet in Hawaii for talks in the second week of March, a source familiar with the planning of the meeting said on Friday, potentially pushing back the timing of a final agreement on the pact.

Australian Trade Minister Andrew Robb said on Feb. 5 he hoped to reach agreement on the bulk of the Trans-Pacific Partnership between mid-February and mid-March and Mexican Economy Minister Ildefonso Guajardo said on Jan. 22 a mid-March deal was "feasible."

But no date has been set for a ministerial meeting to make final decisions on politically sensitive issues such as how long drug companies can have a monopoly over new medicines and the enforcement of environmental provisions in the pact. The agreement would stretch from Japan to Chile and cover 40 percent of the world economy.

The U.S. Congress has yet to debate key trade legislation, and Japan's economy minister said on Wednesday reaching an agreement in spring was "becoming difficult."

The chief negotiators meeting, planned for March 9-15 in Hawaii, may prepare the ground for ministers to meet later.

"We expect there will be some agreements that will need to be handled at a higher level and when the time is right to do that, we will," U.S. Chief Agricultural Negotiator Darci Vetter said late on Thursday.

One hurdle to completion is the lack of U.S. legislation to streamline the passage of trade deals through Congress. Such a law is seen as key to encouraging final offers from the 11 non-U.S. countries participating.

Senator Orrin Hatch, the Republican chairman of the Senate Finance Committee, has said he hopes to introduce a bill in February and he has called a hearing before his committee next Thursday to discuss the trade agenda.

But a spokesman for Senator Ron Wyden, the top Democrat on the panel, said Wyden believes a hearing is premature given the lack of agreement on the trade promotion authority legislation, which would restrict Congress to a yes-or-note vote on trade deals in exchange for setting negotiating objectives.

Republicans are happy with a draft bill introduced last year, which never progressed to a vote, but Wyden is pushing for more provisions on Congressional oversight and transparency. The White House is keen for Congress to pass the bill.

A Hatch spokeswoman said the meeting would give members a chance to discuss trade priorities.