When the Ohio congressional delegation gathered recently to discuss plans for periodic luncheons, lawmakers wondered if they could use campaign or office funds to pay for them. Get a written opinion, his colleagues recall Sen. John Glenn (D-Ohio) as saying, only partly in jest.

As one of the "Keating Five," who are nearing the end of a grueling 14-month investigation into the ethics of their ties to savings and loan executive Charles H. Keating Jr., Glenn is understandably cautious.

But he is not alone. Many senators say they are scrutinizing activities that could get them in trouble with the Senate ethics committee, even practices they once assumed were routine.

Some say they are consulting their consciences more often than before. Others feel safer consulting the ethics committee, which reports a substantial increase in the number of inquiries about proper conduct from senators in each of the past several years.

Their concerns run the gamut from the propriety of congratulatory notes to the extent to which a lawmaker can intervene with a federal regulatory agency on behalf of a constituent, especially when that constitutent is also a contributor.

"Do you know that it's against the rules to send congratulations to high school seniors?" asked Sen. Richard H. Bryan (D-Nev.), who has turned to the ethics committee for guidance on this and other questions since coming to the Senate two years ago.

"It's like waltzing through a minefield," said Sen. Thad Cochran (R-Miss.), who insists that common sense is still the best guide.

The question of intervention will be decided by the ethics committee when it rules on whether Sens. Alan Cranston (D-Calif.), Dennis DeConcini (D-Ariz.), John McCain (R-Ariz.), Donald W. Riegle Jr. (D-Mich.) and Glenn intervened improperly with federal thrift regulators on behalf of Keating, a major contributor to their campaigns and political causes.

In addition to phone calls and letters, the senators met as a group with regulators in what the regulators said they regarded as pressure to go easy on Keating's Lincoln Savings and Loan. The thrift ultimately was seized by the government at a cost of $2 billion to taxpayers.

The committee concluded two months of public hearings on the cases last month and is expected to make a decision shortly on whether any or all of the senators violated ethics rules and merit disciplinary action.

The senators' intervention raised a number of questions that are not covered by specific Senate rules, such as how far a lawmaker can go in pleading a constituent's case or pressing for a specific action, as opposed to making inquiries and urging a fair outcome. There is also concern over where to draw the line when the constituent is also a contributor or when the agency is a quasi-judicial regulatory body.

Committee members already have indicated that they do not intend to curtail constituent service. During the hearings, several made it clear that they consider vigorous intervention, even with regulatory agencies, to be an essential part of the responsibility of a lawmaker -- and the power of the legislative branch of government.

But, with varying degrees of intensity, many senators appear to be taking a second look at how they handle constituents' requests for help, and some have embarked on elaborate screening, monitoring and record-keeping operations that one aide likens to "an archivists' full-employment act."

"At least we're all probably proofreading letters a whole lot more -- and making sure we keep copies of everything," said Sen. Richard G. Lugar (R-Ind.).

Perhaps the most exhaustive effort has been launched by Senate Minority Leader Robert J. Dole (R-Kan.), who has proposed new rules for dealing with federal regulators as part of a campaign finance and ethics package but is not waiting for Senate action to impose the new rules in his own office.

Dole has circulated copies of his new rules to other Republican senators. Several said last week they are considering adopting Dole's rules or drafting their own set of ethical safeguards.

In addition to an earlier practice of collecting and retaining all written communications, Dole now requires all staff members to keep logs of unwritten contacts with federal agencies involving civil or criminal enforcement actions or award of agency contracts, including any requests for information or recommendations for action. Twice a month the logs are to be forwarded to Dole's top aides.

"Err on the side of disclosure," the policy suggests.

Staff members are prohibited from contacting an agency and recommending a specific action in enforcement or contract cases, such as reduction of fines or special consideration for a particular bidder, unless personally authorized to do so by Dole.

"Although this policy imposes a small paperwork burden on us all, I believe that the burden is far outweighed by the need to keep an accurate accounting of staff contacts with federal agencies," Dole said in his letter to Republican colleagues.

Dole earlier enunciated what he calls a "front-page" standard: "If we do intervene with a federal regulator on behalf of a constituent, we should be comfortable reading about the intervention on the front page of the newspapers."