Tom C. Korologos, a high-powered corporate lobbyist with strong ties to the Republican Party, has carved out an unusual specialty: the representation of Reagan administration appointees facing tough Senate approval fights.

Working free -- but getting invaluable public exposure of his close ties to key administration figures -- Korologos has emerged as the key confirmation strategist behind controversial appointees such as Edwin Meese III (attorney general), William P. Clark (interior secretary), Kenneth L. Adelman (director of the U.S. Arms Control and Disarmament Agency) and Alexander M. Haig Jr. (secretary of state).

"If you see any downside, I'd like to know about it," said Patrick J. O'Connor, a Democratic lobbyist, one of whose partners has helped Korologos handle past nominations.

"If you had to call one of the people represented in a confirmation hearing , I think he'd answer your telephone calls," O'Connor added, referring to one of the ways Korologos' volunteer services can be repaid.

"It's a labor of love," Korologos said. He is a partner in Timmons & Co., whose clients include the American Petroleum Institute, Anheuser-Busch, Boeing, H.J. Heinz, G.D. Searle, Northrop and Standard Oil (Indiana).

Until recently, Korologos was batting 1,000 on difficult nominees. "But now, I'm four out of five," he said, referring to the Senate Judiciary Committee's rejection of William Bradford Reynolds as associate attorney general.

Korologos learned his specialty in the trenches, working as a paid White House lobbyist for Richard M. Nixon and Gerald R. Ford. Among the tough confirmations he coordinated in those years were the vice-presidential selections of Ford and Nelson A. Rockefeller, the appointment of Henry A. Kissinger as secretary of state and of William B. Saxbe as attorney general.

In late 1980 and early 1981 Korologos was a volunteer member of the Reagan transition team, helping most members of the new Cabinet through the confirmation process.

All this experience, he said, has taught him basic lessons that he passes on to his "clients." The most important is to recognize that the function of a nominee seeking Senate approval is to "act like a bridegroom: shut up and get to the wedding on time."

Another warning he gives is, "The Constitution stops at the hearing door. They [senators] can ask anything, questions that would never be admissible in court -- hearsay, rumors, anything."

Finally, he said, a nominee should never "go near the place [his prospective office], not even to measure the chair. It's an affront to the Senate."

As he has developed his specialty, Korologos has become known among aficionados of Senate proceedings as "the Edward Bennett Williams of confirmation cases." Williams is a Washington lawyer with a reputation for taking on tough cases.

Korologos' reputation is such that he once went to a nomination hearing room with no interest in the nominee, but simply to talk to a senator; people began to whisper, "Is the nominee in trouble?"

As a rule, Korologos said, the nominees most likely to have trouble are those who have written controversial books or those with a record of federal service, such as Reynolds, who is assistant attorney general for civil rights.

Korologos said one of the virtues of his work is that "nobody can fire me." But when he takes on a nomination, he does not just sit on the sidelines offering casual advice.

During the Meese hearings, for example, Korologos ordered Meese's attorney, Leonard Garment, to stay out of the hearing room altogether when Garment's billing charges became a source of controversy. Garment reportedly was infuriated, but acquiesced. (Garment could not be reached for comment.)

Korologos' activities have provoked private complaints from some who point out that the same person who represents defense contractors, a federally regulated network, American Broadcasting Companies, and numerous companies with vital interests in tax policy is simultaneously representing members of the Cabinet and some of their most important subordinates.

Korologos dismisses these complaints as sour grapes from people he has often beaten:

"Their problem is they lose every time they fight me. I'd complain every time if I lost. I'm a free citizen. I can do anything I want. I have a constitutional right to petition the government."