Senate backers of Israel this week will face their first test since the Oct. 8 shootings of Moslem demonstrators in Jerusalem, when they attempt to gain additional concessions for Israel in foreign aid spending legislation.

A group of senators who contend that the Iraqi threat to Israel has increased dramatically plan to introduce an amendment that would give President Bush special authority to transfer up to $700 million worth of Defense Department stocks of weapons and equipment to Israel.

Sen. Arlen Specter (R-Pa.) described the plan as a "Lend-Lease concept," a reference to America's material support for Britain before the U.S. entry into World War II. The House version of the foreign aid bill was completed before the Persian Gulf crisis erupted. Since then, a number of concessions to Israel have been attached to the measure as it moved through the Senate Appropriations Committee.

The so-called "foreign operations" appropriations bill is one of 13 spending measures that Congress passes every year. These bills, with a total value of some $500 billion, pay for most federal programs, defense, and the operations of government. As frequently happens with these bills, this one has been caught in a last-minute political wrangle that has little to do with the programs it finances.

Late Friday night, debate was halted when Republicans objected to consideration of an amendment by Sen. Timothy E. Wirth (D-Colo.) to overturn long-standing policy that bars the use of U.S. funds by population groups that promote abortion.

Republicans, who believed they had an understanding with Majority Leader George J. Mitchell (D-Maine) not to pursue the issue, reportedly were furious. Anti-abortion forces, led by several senators who are not seeking reelection, have threatened to filibuster. Abortion-rights supporters doubt they have the 60 votes needed to close off debate.

Caught in the middle is the Bush administration, which has been lobbying hard for the Senate bill with its provisions forgiving $7 billion of Egypt's military debt to the United States. Administration officials say a signal of U.S. support for President Hosni Mubarak is even more urgent following last weekend's assassination of Egyptian Parliamentary Speaker Rifaat Mahgoub.

Support for beefing up Israel militarily appears to be strong in both the Senate and House, sources say, despite the Oct. 8 slaying of 19 Palestinian demonstrators by Israeli police. "It's very easy to say use restraint when you're not facing violence," Specter said.

The Senate bill already provides a number of technical concessions to Israel within the U.S. military aid program. In an unusual step, Senate appropriators authorized Israel to use $200 million of economic aid for defense purposes. The bill also sets up a U.S. "war reserves stockpile" of at least $200 million in Israel. These stocks would "provide an additional source of urgent military assistance in the event of an attack on Israel," according to a report accompanying the bill.

Several senators say they want to do more. Under the Arms Export Control Act, the president already has emergency authority to provide another country with up to $75 million worth of equipment from Defense Department stocks if he reports an "unforeseen emergency" to Congress. Negotiations are underway to supply Israel with batteries of Patriot missiles and other equipment under this provision. But the Senate amendment would expand the president's authority to transfer U.S. defense stocks to Israel to $700 million.