The business of writing a package of fiscal 1991 spending bills formally got underway in Congress yesterday and immediately revealed a series of sharp differences between House Democrats and the White House on budgetary priorities ranging from U.S. aid to Africa to missions to Mars.

The most dramatic sign of early discord emerged in the drafting of the foreign aid bill when Rep. Mickey Edwards (Okla.), ranking Republican member of the Appropriations subcommittee on foreign operations, announced that he could not support the measure if it went to the floor as written.

Citing a $325 million cut in overall military assistance recommended by Rep. David R. Obey (D-Wis.), the subcommittee chairman, Edwards declared: "It is simply unacceptable."

Edwards later said that he also had "enormous problems" with bill language limiting military aid to El Salvador to $85 million, and containing a provision to cut that in half if the government there impedes peace talks with rebel guerrillas or fails to continue investigations into the murder last year of six Jesuit priests. The sharply divided subcommittee agreed to send the El Salvador issue forward so it could be thrashed out on the House floor.

The foreign aid flap set the theme for a day in which the full House Appropriations Committee completed work on two other spending measures, and prepared to take up another appropriations bill funding space, veterans' and housing programs.

The bill-writing took place against a backdrop of extreme uncertainty -- and, some said, unreality. The appropriators are operating without a budget summit agreement between Congress and the administration or a congressional budget resolution to guide them. As a result, they have decided to keep their total spending within the bounds of President Bush's budget, but to reshuffle the numbers to fit the priorities recently agreed on in a resolution passed by the Democratic-controlled House.

A dramatic example came in the totally revised priorities adopted Tuesday by the subcommittee that funds veterans', space and housing programs. The subcommittee slashed funds for Bush's high-priority Moon-Mars mission, cut the administration request for the toxic waste Superfund by $129.8 million, but added a record $4 billion to the president's request for subsidized housing, raising the total to $11.6 billion.

Administration officials indicated yesterday they will seek special treatment for the National Aeronautics and Space Administration to prevent its budget from being raided for non-space programs. Generally, NASA appears not to have fared badly But funds that now appear available could evaporate later as the deficit picture becomes clearer.

Pent-up constituent pressure on Congress was evident in the energy and water appropriation bill reported out by the committee yesterday. It includes funds for 25 new river and harbor initiatives and adds $487 million for nuclear waste cleanup, but cuts funds for the Nuclear Energy Directed Weapon, used in the Strategic Defense Initiative.

Symbolizing frustration with administration China policy, the foreign operations subcommittee voted to withhold the U.S. share of funds for the World Bank if new loans to China are for anything other than basic human needs. It increased the administration's requested aid to Eastern Europe from $230 million to $430 million. It also placed new, lower ceilings on military aid to Greece and Turkey.

Staff writer Kathy Sawyer contributed to this report.