Members of both parties say they will try to ease a 10 percent cut in NASA's budget that has been approved by a House subcommittee.
Rep. Alan Mollohan, D-W.Va., criticized the "enormous, devastating" reduction in the space agency's budget.
NASA Administrator Daniel Goldin said such cuts, if ever enacted, would result in the agency having to lay off workers, close two or three of its 10 centers and sustain delays in deploying the space station.
"We're talking about gutting space exploration," he told reporters.
Subcommittee Chairman James Walsh, R-N.Y., the bill's chief author, said the cuts in space spending were "perhaps the most difficult and painful choices" he made in writing the measure.
Referring to that and other reductions, he said he would "make every effort to address these difficulties" later this year, when the legislation is likely to be part of budget negotiations with the Clinton administration expected to result in higher spending.
Under the legislation, NASA would get $12.3 billion for fiscal 2000, which begins Oct. 1. The space agency received $13.7 billion this year, and President Clinton requested $13.6 billion for next.
The measure would provide $2.4 billion for the international space station, one of NASA's highest priorities. That's $100 million more than this year, only half the boost Mr. Clinton requested.
It is elsewhere that NASA would feel the pinch. The legislation would deny the president's $150 million request for future missions of the Earth observing system, which studies climate, and would trim $75 million from future Mars exploration missions. The space shuttle would get $150 million less than Mr. Clinton wants.
The bill's cuts reflect the GOP's efforts to try living within spending limits enacted in 1997 in the budget-balancing agreement with Mr. Clinton.
To help stay within those limits, the subcommittee would designate $3 billion in veterans health-care spending and $2.5 billion in disaster assistance as "emergencies."
Under budget law, that means those items would be exempt from spending limits. Mr. Clinton had proposed making the disaster spending an emergency, but not the veterans' money.
The panel also claimed savings by reducing the Tennessee Valley Authority's ability to borrow by $3 billion - loans the agency is not expected to seek anyway.
The bill would provide $7.3 billion for the Environmental Protection Agency, $100 million above Mr. Clinton's request but nearly $300 million below this year. Within that total, it would provide $115 million for climate change technology - a favorite of Vice President Al Gore and just half the administration's request.