Washington — Congress is beginning to grope for ways to regain its lost controls following the recent historic Supreme Court decision that swept away the legislative veto. So far, all signs point to a long, difficult search. That became clear last week as the House added amendments to a Consumer Product Safety Commission bill. Before the court ruling, Congress had the power to overturn safety commission rules on consumer items ranging from lawn mowers to pacifiers. Now that veto power has been found unconstitutional on grounds that it usurps the authority of the executive branch of the federal government.
In its effort to devise a new plan for overseeing the agency, the House added not one but two systems. Rep. Henry A. Waxman (D) of California tacked on an amendment that would delay new safety rules for 90 days, giving Congress time to repeal the rule by a federal statute.
But Rep. Elliott H. Levitas (D) of Georgia, a longtime supporter of the legislative veto, wanted double protection. He won approval for an amendment that would withhold enforcement funds for any new safety commission rule until the rule passed both houses and was signed by the president.
Not only do the two plans go off in quite different directions, but even their proposers admit they were casting about for substitutes to the veto. ''I predict this will be the first of many, perhaps even hundreds, of occasions where we are going to have to restructure this delicate balance between the executive and the legislative branches of government,'' said Representative Levitas.
Moreover, Congress cannot be certain whether the new plans will be constitutional.
''I'm concerned about moving into the gray area,'' said Stanley Brand, general counsel to the clerk of the House. He said last week that the proposed 90-day layover for new rules clearly conforms to the court decision, but that the Levitas plan raises doubts.
In committees and offices all over Capitol Hill, Congress is assessing the damage done to up to 300 statutes that now involve some kind of legislative veto.
Members and their staff are taking a hard look at one of the most important laws affected, the 1973 War Powers Act. Passed in response to the Vietnam war, it gave Congress the power to recall troops that a president has dispatched to foreign hostilities.
Although Congress never tested its power to bring troops home, the act gave the legislators a threat to hold over the White House. In part because of the War Powers Act, American military advisers are not allowed to go into battle with Salvadorean soldiers.
Leaders of the Senate Foreign Relations Committee last week gave assurances that most of the War Powers Act remains intact. The law is ''not repealed or undone'' by the court decision, said the committee chairman, Sen. Charles H. Percy (R) of Illinois, and its ranking Democrat, Sen. Claiborne Pell of Rhode Island, in a statement.
While the veto provision is in trouble, the act includes other safeguards that are still in effect. The president is required to consult with Congress if he decides to send troops into foreign battles. The law also prohibits keeping American troops in foreign wars for longer than 90 days unless Congress passes a specific authorization.
Despite assurances that most of the War Powers Act is still operating, some members of the Senate are not satisfied. The Senate Democratic Policy Committee is preparing a rewrite of the law to strengthen congressional controls.
''Once those troops are committed, it's always difficult to take action,'' said a Democratic aide. One plan under study is to require that Congress pass a joint resolution either of approval or disapproval within 60 days after the president has sent troops abroad. Such a resolution would require a presidential signature, just as any act of Congress.
The loss of the legislative veto also threatens congressional power to force the president to spend money it has appropriated. Under the 1974 budget act, the president can defer spending only if Congress does not override the deferral.
But the Supreme Court ruling has reopened questions about what happens when the president wants to delay spending.
Potentially, it could put a powerful cutting tool in the hands of David A. Stockman, director of the Office of Management and Budget (OMB).
Edwin L. Dale Jr., a spokesman for the OMB, said last week it was ''premature'' to try to determine the impact of the court ruling. He pointed out that most deferrals of spending are routine, such as a delay in building a road because of flooding.
''There will have to continue to be deferrals,'' said Mr. Dale, adding that ''what is not clear is the congressional right'' to overturn those few deferrals that are controversial.
''Everybody is looking at it (the court ruling) without knowing what it all means,'' said a spokesman for the House Budget Committee. He suggested Congress may now require an act every time the president wants to defer spending for a project.
In large part, such ideas have not even arrived on the drawing boards, however.
''I don't think Congress is going to be successful for a while in recapturing the control it had,'' said Louis Fisher, an American government specialist with the Library of Congress. But when it does, he predicts that it will eventually take back more than it had before.
''The executive branch had been delegated more discretion'' with the veto, said Mr. Fisher. Without the veto, he predicted, Congress will tighten up the controls and delegate less.
Some in Congress are pleased with the court ruling. Rep. Joe Moakley (D) of Massachusetts said last week that ''the decision should not be viewed as a disaster or as a victory for anyone.'' Congress ''will be forced to write laws with greater specificity,'' he said. Mr. Moakley is proposing hearings on the decision later this summer in his rules of the House subcommittee.
Untangling all the snarls created by the Supreme Court ruling could be a slow process. ''It took the court only 18 months'' to destroy the legislative veto process which has been built up over 50 years, said Mr. Brand. Congress must now change its focus, he said. ''That's not going to happen overnight.''