WASHINGTON - Robert Carlyle Byrd, former butcher, grocer and shipyard welder, quietly relinquishes one of the most powerful elective offices in the nation this week.

Byrd is stepping down as majority leader of the Senate, the 15th person to hold that position. He leaves confident he has revitalized the Senate's role in American government, but doubtful his successor can stem growing complaints that life in the chamber isn't what it should be.Tempered by poverty in the West Virginia coal fields where he was raised early in the century, Byrd, who turned 71 last week, has little sympathy for the complaints of younger men who see the Senate as a cumbersome body that works too late, too often.

"We can't operate on a punch-the-clock basis," says Byrd, who was elected to his sixth, 6-year term on Election Day. "I did that once - when I was a welder in a shipyard."

His successor as leader of the Senate will be elected Tuesday when the 55 Democratic senators of the 101st Congress gather for an organizational meeting in the Capitol.

The majority leader, a position formally recognized in 1911, controls the Senate's schedule, including which bills are considered and when they are debated.

For the first time since his election as majority whip in 1971, Byrd won't be running for a leadership role. But he won't be without power, as he assumes the chairmanship of the Senate Appropriations Committee and becomes president pro tempore - the senior statesman - of the Senate. That also puts him third in line for the presidency, behind the vice president and the speaker of the House of Representatives.

"I look back on my years as leader with satisfaction," the silver-haired senator said in an interview in his Capitol office suite last week. He has served as leader of his party in the Senate since 1976, half that time as majority leader.

"I have brought the Senate back to where it is now a stronger voice than it had been for a while," Byrd said. "I have insisted on checks and balances with the executive branch to make it a potent and strong force."

Explaining how he "revitalized the Senate's unique role," Byrd refers to the Senate's exhaustive work in approving President Reagan's missile treaty with the Soviet Union and its rejection of Robert Bork and subsequent approval of Anthony Kennedy for the Supreme Court.

Looking ahead, Byrd is skeptical about the election promises of those seeking to replace him as majority leader.

"I don't intend to offer advice," Byrd says. "They're all three capable and expert on legislation and each has his own special talents."

The three, Daniel Inouye of Hawaii, Bennett Johnston of Louisiana and George Mitchell of Maine, each are promising to improve the "quality of life" in the Senate. By "quality of life," they mean to shorten a grueling regime of long hours and unpredictable schedules.

"I believe first in the quality of work," Byrd said. "One can't adjust the needs of the nation to one's comfort."

He believes the task facing his replacement, and Congress in general, is daunting.

"The hangover will soon be felt," Byrd said of the budget deficit and national debt crises facing the Bush administration and the Democratic-controlled 101st Congress.

"We've got a very terrible problem that will be overriding," Byrd says. "Congress will work with Mr. Bush. But he has to show leadership.

"He comes to the presidency a more knowledgable man, with a respect for the federal government," Byrd says of the president-elect.

Byrd grimaces at the mention of the outgoing administration and offers two observations of Ronald Reagan, whom he has criticized often for his confrontational approach to the Congress.

"One, he's a very charming and likable man. Second, he's going to leave a legacy our children and grandchildren will pay for - a national debt. We were the world's greatest creditor eight years ago, now we're the world's biggest debtor nation."

Looking back - to before Reagan came on the Washington scene and to his own beginnings in Congress - Byrd says he holds two former presidents in highest regard:

"My favorite Democratic president was Truman. I served under him for 17 days," Byrd says, referring to the brief transition period when he was taking his seat in the House of Representatives in 1953 and Harry Truman was turning the White House over to Dwight Eisenhower.

The Republican president he holds in highest regard was Richard M. Nixon, a man he describes as "very, very able, equipped to be president. He understood government and he knew how to work with Congress."

Byrd puts his retirement as majority leader in historic perspective.

A man who often takes to the Senate floor to quote poetry and read history, Byrd says he is retiring, like Cincinnatus, the 5th century B.C. Roman farmer-statesman who twice left his fields to save Rome in crisis, only to return to the farm.

Byrd isn't returning to any farm. But, he says with a smile:

"Like Cincinnatus, I'm going back to the plow."