Shortly after President George H.W. Bush nominated him for the Supreme Court in July 1991, Clarence Thomas went to a downtown Washington office to take part in strategy sessions aimed at ensuring his confirmation by the Senate.

The presiding political mind was not a top White House aide or a legal eagle from the Justice Department but lobbyist Kenneth M. Duberstein, a former Reagan administration official who was Thomas's designated "sherpa" -- his guide through the potentially treacherous process.

Duberstein, then and now, is one of a handful of Washington figures who have acquired reputations for steering top presidential nominees through a confirmation process that has grown more contentious and partisan since the unprecedented campaign that capsized Judge Robert H. Bork's Supreme Court nomination in 1987.

The role of the sherpa, named for the Tibetan guides who assist climbers in the Himalayas, is largely off camera and unpaid. It is a critical and routine part of the Washington odyssey that high-profile nominees go through on their way to the high court or top Cabinet posts.

When John G. Roberts Jr. was nominated by President Bush in July to be an associate justice, he was promptly provided with two guides: former senator Fred D. Thompson (R-Tenn.) and former Republican National Committee chairman Ed Gillespie. Both are considered savvy Washington insiders who are now comfortably on the outside. After the death of Chief Justice William H. Rehnquist last week, Bush nominated Roberts to lead the court.

Roberts has not faced anything like the opposition Bork did. Democrats say they will press him harder at his confirmation hearings beginning Monday now that he is in line to be chief.

"There are several roles you play," said Duberstein, who also served as a guide for Supreme Court Justice David H. Souter, CIA Director Robert M. Gates and Secretary of State George P. Shultz. "You are the chief strategist for the ultimate goal of getting that person confirmed. You are also the traffic cop, because everybody wants to see the prospective nominee. You are a coach and you're also a confidant of the nominee. You are the chief liaison with the Hill, but also the chief liaison within the administration. You are an enforcer, but you are also a negotiator."

Duberstein said the job of guiding Roberts should not change because he has been nominated for chief justice. "I don't recall that there would be any distinction," he said.

The sherpa is very much the media messenger -- shaping and selling a nominee's personal story and image, devising strategies for dealing with reporters, and coordinating courtesy calls with key senators.

"They'll school you on what to say and what not to say," said Paul C. Light, a professor of government at New York University. "They are kind of a sounding board for you, and whenever you have one of those anxiety attacks . . . they are counselors for you. And if you get into trouble, you get a 'hold' placed on you, then they'll help you iron it out."

Sherpas tap their sources on Capitol Hill to learn about tough questions a nominee might face, and then drill nominees in mock confirmation hearings known as "murder boards." They even coach them on such matters as how long to pause before answering a senator's question and how to ask for a bathroom break.

But this is a complex process, and even the helper needs help. Sherpas supervise teams that vet a nominee's financial statements, personal history and professional record -- trolling for red flags.

Light likened them to personal trainers, "somebody who is going to be there while you are doing everything and keep you from hurting yourself."

Other well-known sherpas include longtime Republican lobbyist Tom Korologos, now ambassador to Belgium, who helped Donald H. Rumsfeld (secretary of defense), Antonin Scalia (Supreme Court justice) and Edwin Meese III (attorney general), and veteran Democratic strategist Michael S. Berman, Duberstein's lobbying business partner, who assisted Justices Stephen G. Breyer and Ruth Bader Ginsburg.

Although sherpas work pro bono, the job is not without compensation. The role underscores a lobbyist's political access and clout, impressing prospective corporate clients.

Duberstein and then-Sen. John C. Danforth (R-Mo.), assisted by a team of administration insiders, helped steer Thomas through a difficult confirmation marked by law professor Anita Hill's accusations that Thomas had sexually harassed her when she worked for him at the Education Department and the Equal Employment Opportunity Commission, in the 1980s. Duberstein was especially influential on matters of style, Danforth wrote in his 1994 book, "Resurrection: The Confirmation of Clarence Thomas."

"As Clarence walked past banks of cameras, Ken would say, 'Give them a thumbs up,' and Clarence would comply," Danforth wrote. "When advising Clarence not to respond to press questions, Ken suggested, 'Tell them, "I wish I could answer that." ' . . . He told Clarence that when he entered the Senate Caucus Room at the start of his first hearing, he should go up and shake hands with each member. He insisted that Clarence, against his will, conclude the first hearing by complimenting the committee for being fair."

Thomas prevailed, in part, because he was able to define himself as an African American who had risen from poverty in rural Pin Point, Ga., and whose confirmation controversy represented yet another hurdle that he had to overcome. In a tactical move, Duberstein won assurances from the Senate Judiciary Committee that Thomas would have the opportunity to respond to any allegation in the same news cycle. That enabled Thomas to reclaim the offensive on the day Hill testified and Thomas responded by memorably labeling the proceedings "a high-tech lynching for uppity blacks."

When Rumsfeld was sworn in as defense secretary in 2001, Korologos was in the Oval Office with Bush and Vice President Cheney. "He is so famous for working around outside the Senate chamber that he is known by the insiders as the 101st senator," Rumsfeld said at a March 2002 award ceremony for Korologos. "But all that experience does come in handy, and it has helped me from time to time -- not least in my confirmation hearings. His advice for courtesy calls was 'Get in, listen, get out.' It worked."

Korologos has handled hundreds of nominations over the past 40 years, most of them uncontroversial. He has even helped with three or four murder boards by telephone from Brussels, he said.

"It's an arcane art," he said in a telephone interview. "Most nominees have never done this before. . . . You are not running for sheriff; you are not running for Miss America. You are running for whatever the number is, 10 or 11 votes on the committee and 51 on the floor. That's the constituency."

Carol M. Browner, head of the Environmental Protection Agency in the Clinton administration, said her sherpa's best advice was that confirmation hearings are mostly about the senators, not the nominee.

"Mike Berman said to me, 'When they finish asking that question, wait a few seconds to reflect on the question. It makes you look respectful. It makes you look thoughtful. And it takes up time,' " she said. "He had all these little tricks."

Exactly, Korologos said. "You've got to know the system, the nuances, what buttons to push up on the Hill to make them respond. That's why there aren't many of us doing it."

As confirmation fights have become in some ways proxy battles in the country's culture wars, the need for sherpas has grown. But sherpas are guides, not guarantees, and nominees occasionally fail anyway. Korologos, for all his skill, handled the Bork nomination for the Reagan White House.

"Washington is like Salem," Korologos said. "If we ain't hanging somebody, we ain't happy."

John Roberts Jr., left, has been guided by former senator Fred Thompson as he visits officials. Roberts's other escort has been the GOP's Ed Gillespie.