The Bush administration, facing rising congressional concern, stepped back yesterday from a plan to sell Saudi Arabia an immense package of arms worth more than $21 billion, and told legislators it wanted to avoid a costly political battle in the midst of the military tensions in the Persian Gulf, according to informed sources.

Senior Defense and State Department officials, who had arranged a series of Capitol Hill briefings on the Saudi arms purchase, were told that broad legislative support could be achieved only for sales of weapons to assist in the current gulf crisis, or just a fraction of the $21 billion total.

Some members of Congress warned that the remainder of what has been described as the largest single arms transfer in U.S. history should be postponed for further study, while others said it might be feasible only if accompanied by extraordinary concessions for Israel.

In Jerusalem, Israeli officials yesterday said the administration has promised to send more F-15 fighters, Patriot air defense missiles, and extra ammunition to Israel, but has deferred action on a request for more than $1 billion in new arms aid. {Details, Page A25.}

Here in Washington, administration officials, including Defense Undersecretary Paul Wolfowitz and Undersecretary of State Reginald Bartholomew, did not insist on the full Saudi sale and promised further consultations with Congress before seeking approval of an arms package that could gain swift and broad congressional approval, the sources said.

"The message {from the legislators} was that they've heaped on the table a lot of things that aren't going to be eaten at this sitting," said a key Senate aide.

Deputy Secretary of State Lawrence S. Eagleburger, like other administration officials, told legislators yesterday that the $21 billion plan advanced by the Pentagon last week had not been formally approved and would be modified to reflect congressional concerns.

He told a hearing of the House Appropriations subcommittee on foreign operations that he did not know what the Saudi arms package would eventually look like, adding, "We are going to consult and consult and consult." Other officials said that because of the wary congressional reaction yesterday, the package would not be submitted for legislative approval before next week.

The massive arms package, including F-15 jets and Apache helicopters that would not be delivered to the Saudis for several years, was developed by the Pentagon in response to administration concern for Saudi Arabia's long-term security. When disclosed last week, many legislators viewed it as a sudden, unwarranted expansion of the several-billion-dollar arms sale initially contemplated in the wake of the Iraqi invasion.

Subcommittee Chairman Rep. David R. Obey (D-Wis.) said he considered the Pentagon plan to be "wildly large . . . grossly oversized." A senior U.S. official, speaking on condition of anonymity, acknowledged that the plan's sudden disclosure, prior to any legislative consultations, appeared to be "a textbook example of how not to proceed in an arms sale."

The official said it was "a valid point" that the administration should separate the arms for the current crisis from those needed over a longer period. Rep. Mel Levine (D-Calif.), who in the past has criticized arms sales to Arab countries, said he detected bipartisan support for this approach after he and other legislators suggested it during a Tuesday appearance on Capitol Hill by Assistant Secretary of State John H. Kelly.

During the briefings yesterday, administration officials did not specify the value of U.S. arms that may be transferred immediately. But Levine said he estimates that "at best, 10 percent of the weapons" will be useful to the Saudis in the near-term, while the remainder will be delivered in one to three years.

Others said the weapons of immediate use to the Saudis included wheeled vehicles and TOW anti-tank missiles and launchers. The precise cost and number of these weapons were unavailable. The weapons to be delivered later would also include hundreds of M-1 battle tanks, Bradley Fighting Vehicles, and naval command and control systems.

U.S. officials initially argued yesterday that the $21 billion sale was less than the Saudis desired and should be approved in its entirety before next month's congressional recess for fall elections. But they did not dispute complaints that this would preclude careful consideration of wider questions such as the impact on Israeli security and future Saudi needs in the aftermath of any conflict with Iraq, sources said.

Several legislators said they told the administration that the Saudi sale could unavoidably alter the Middle East balance of power, despite repeated pledges from Eagleburger and Secretary of State James A. Baker III to maintain Israel's qualitative military advantage in the region.

The Pentagon yesterday formally notified Congress of plans to sell 300 air-to-air Sidewinder missiles to Israel and 220 Sidewinders to Britain for a total of $55 million.

Administration officials have acknowledged that the Israeli and Saudi packages will be linked during congressional deliberations, although formally approved in separate legislation. But they have evidently been reluctant to meet Israeli requests for forgiveness of debt from past arms purchases and immediate access to satellite reconnaissance photos, a circumstance that has fueled pressure to curtail the Saudi package.

The issue has also been complicated by the administration's proposed legislation to forgive a $7 billion Egyptian debt for past arms purchases, which is now before Congress. "If you provide $20 billion to Saudi Arabia, $7 billion of forgiveness to Egypt and additional assistance to Turkey {for cooperation in the gulf crisis} . . . what other kinds of requests do you expect from other countries?" Obey asked.

He added that before any decision could be made on the proposal to forgive Egypt's debt, the details of the offer to the Saudis would have to be known, along with "a lot more information about what the whole cost of this entire package will be."

Bush has avoided involvement in the debate so far, in a move that several officials said was intended to preserve flexibility. But he has endorsed a new effort to arm U.S. allies in the region enough so that future crises will require less U.S. support.

This goal was disputed by several legislators, who told administration officials that it could spark a new arms race and would lead to a false sense of security for friendly states in the region.

Staff writers John M. Goshko and David Hoffman contributed to this report.