Seeking to rein in government regulators, the Senate is about to consider legislation that would radically shift the balance of regulatory power in this town--making it harder for rule makers to issue rules and easier for the White House, the courts, and possibly Congress, to challenge the few rules that succeed in clearing the new regulatory maze.

For one thing, the legislation would force regulators to follow stricter guidelines and go through lengthier proceedings before they can issue rules. Agencies would also be required to conduct detailed cost-benefit studies before any major rule could even be put out for public comment.

At the same time, the legislation would create new opportunities for rules to be challenged and overturned. The White House would have the authority to review the major actions of all agencies--including the so-called independent agencies, such as the Federal Trade Commission and the Securities and Exchange Commission, that up to now have only been responsible to Congress, not the president.

Additionally, opponents would have a greater chance of getting rules overturned in the courts because the legislation would shift the burden of proof in defending a rule. Where challengers now have to prove the rule is unfair, the legislation would make the agencies prove the rule is necessary.

When introduced nearly a year ago, the regulatory-reform legislation seemed like a sure thing. Not only did 79 senators cosponsor the legislation, but the business community was also pushing for its passage.

But today, the prospects for passage are growing dimmer by the day.

For one thing, the bill is months behind the schedule set when it was introduced. Its sponsors--chiefly Sens. Paul Laxalt (R-Nev.) and Patrick J. Leahy (D-Vt.)--had hoped to have the measure before the Senate last fall. But an attempt to compromise some of the bill's most controversial sections pushed that date back considerably.

The press of other business has kept the legislation off the floor for many weeks--particularly as several senators threatened lengthy debates over several key amendments. After weeks of delay, the bill had been scheduled for debate today, but the Senate has not yet completed other pending business, making it likely that the bill won't be considered before next week at the earliest.

As a result, the House will have relatively little time to consider the measure in this short, election-year session, especially with the press of budget and appropriations bills.

But the bigger blow to the bill's supporters was the departure last week of Rep. George E. Danielson (D-Calif.), the chief sponsor of a similar measure in the House, to assume a judgeship in California.

"Danielson's departure is a serious blow to the legislation," said one administration official, adding that no one in the House leadership appears to be committed to the bill.

Ironically, the administration also may have contributed to the bill's demise. Even though the administration has made it clear it wants to cut red tape and paper work, it has never been enthusiastic about the legislation, fearful that once Congress started meddling in regulatory reform, it would restrict some of the authority the White House has assumed to review rules. At the same time, it feared Congress would give itself and the courts more power to overturn regulations.

Nonetheless, the administration has been working for the legislation's passage in the Senate, primarily, sources say, so it won't antagonize Laxalt, one of the president's friends and advisers.

However, its support could wane in the House, particularly if the Senate approves an amendment that would give Congress the power to veto any rule--no matter how minor--by a majority vote in both houses. At the moment, one business lobbyist says, the amendment "has a 50-50 chance." If it passes, he adds, "it is a killer" because the administration will no longer push for the bill--and may actively oppose it--in the House.

Under the Senate legislation, regulators could not even propose a major rule--one having an annual cost of $100 million or more--unless they had first conducted cost-benefit analyses to make sure the regulation is needed, that its benefits outweigh its costs and that the rule is the most cost-effective of all the alternatives.

The Office of Management and Budget would have the authority to make sure all agencies comply with this new rule, including the independent agencies.

Business groups have applauded the bill, saying that broad legislation to change the rule-making process could reduce the "adverse impact of excessive regulation."

But consumer groups charge that the measure will impose new delays and burdens on regulators and make it increasingly difficult for badly needed rules to be issued. They also are concerned that OMB will have even more power than it has now to veto regulations.

Amendments to limit OMB's power are almost certain to be attempted in the Senate--unless the administration can succeed in coming up with a compromise.

The amendment likely to trigger the biggest debate is a proposal by Sen. Dennis DeConcini (D-Ariz.) that would specify that when a number of suits involving the same rule are filed in different federal courts, the case would be heard in the court where the action would have the largest impact, not the court in which the first suit was filed, as is now the case. In large part, this is designed to move suits from the federal courts in the District--thought to be among the nation's most liberal--to other parts of the country.

This amendment is supported by business but opposed by consumers.