NEW DELHI--A day before the deadline for a global agreement to ease trade restrictions, U.S. officials said they hoped India would drop its strident objections and allow the deal to move forward.

U.S. Secretary of Commerce Penny Pritzker said in an interview in Mumbai with the Press Trust of India that Washington was "very disappointed" with India's threat to derail the World Trade Organization pact, but added she remained "optimistic" New Delhi would change its stance.

India has said it won't sign off on the WTO trade-facilitation deal, which must be approved by all 160 member governments to take effect, unless the Geneva-based body loosens restrictions on countries' ability to subsidize farmers and stockpile food. India says it needs more leeway to protect its poor citizens.

A spokesman for India's Foreign Ministry declined to comment. Trade officials didn't respond to requests for comment.

A failure Thursday--the deadline the WTO set when members first agreed on the trade measures last December--would be a blow to U.S. officials as they sit down in the Indian capital for an annual strategic dialogue between the two countries. U.S. Secretary of State John Kerry arrived in New Delhi Wednesday evening for the U.S.'s first high-level talks with India's new government.

Indian Prime Minister Narendra Modi and his Bharatiya Janata Party won a resounding victory in this spring's parliamentary elections after pledging to reinvigorate the economy and signal to the world that India is open for business.

But the new government is sticking to its predecessor's position that India should be allowed to pursue agricultural-support programs whose scope is limited by WTO agreements.

At issue are India's massive purchases of rice and wheat from farmers at above-market prices. Part of that grain is kept in government reserves, and the remainder is sold to needy households at subsidized prices. But WTO rules currently allow governments to stockpile food only if they both acquire those stocks and sell from them at market prices.

New Delhi says its agricultural programs help safeguard growers' livelihoods and provide affordable nourishment to the country's millions of poor and vulnerable.

Otherwise, subsidies provided through such programs count toward an annual ceiling for developing nations of 10% of the value of total agricultural production. India, home to a third of the world's extremely poor, according to the World Bank, says restrictions on "trade-distorting" subsidies amount to an assault on its ability to provide for its neediest citizens.

Disagreements about India's agricultural policies flared up at a WTO meeting last December in Bali, Indonesia. India and other developing nations had proposed to exempt government food stockpiling from WTO subsidy caps as long as it is specifically aimed at supporting poor farmers.

WTO members agreed on the package of trade-easing measures that they need to ratify by Thursday. But consensus on the Indian proposal was elusive. Instead, the governments agreed that they would refrain from filing formal complaints against developing countries' food-security programs for the time being. The members set a 2017 deadline for a permanent accord on the issue.

"India has a decision to make about where it fits in the global trading system," Mr. Kerry said in a speech Monday in Washington. "India's willingness to support a rules-based trading order and fulfill its obligations will help to welcome greater investment from the United States and from elsewhere around the world."

The Indian government has budgeted 1.15 trillion rupees ($19 billion) this year for food subsidies, or 6% of total spending. At the beginning of this month, official reserves of rice and wheat exceeded 61 million metric tons, more than double the government's recommended buffer level of 25 million tons.

Those stockpiles are currently being ramped up as India implements a law, passed last year, that will expand food-welfare programs to cover a majority of the country's 1.2 billion people. But mismanagement, inadequate storage facilities and theft prevent a large share of that food--40% to 60%, according to various estimates--from reaching the intended beneficiaries.

William Mauldin and Niharika Mandhana contributed to this article.

Write to Raymond Zhong at raymond.zhong@wsj.com

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