Updated

WASHINGTON -- The Obama administration is expected to notify Congress on Wednesday of a multibillion-dollar sale of fighter jets and military helicopters to Saudi Arabia, officials said Tuesday.

The State Department scheduled a news conference for Wednesday to announce the deal, the officials said, speaking on condition of anonymity because the notification had not yet been made.

The sale of as many as 84 new F-15 fighter jets and three types of helicopters, including the sleek Black Hawk and the missile-toting Apache, would be worth an estimated $60 billion. Pentagon officials have said they expect the Saudis initially would select about $30 billion worth of aircraft. Approval of the larger proposal would give the kingdom room to buy more warplanes later.

The deal, which has been in the works for months and was revealed publicly in September, is designed to counter the rise of Iran as a regional power.

After the official notification to Congress, lawmakers would have 30 days to block the deal. Strong opposition from some lawmakers and some supporters of Israel is considered likely but is not expected to stop the sale.

Iran is now seen by Israel, the Gulf Arab states and the West as a significant and unpredictable threat that has changed the old calculus of the region's balance of power.

The United States is realigning its defense policies in the Persian Gulf as Iran improves the range and accuracy of missiles and other weapons that could threaten Israel or U.S. allies in Europe.

U.S. and other diplomats said Defense Secretary Robert Gates laid out the reasoning behind the proposed Saudi sale during meetings with Israeli Defense Minister Ehud Barak in recent months.