WASHINGTON -- He's 77, has been on the job for more than three decades and has a bad back, so retiring to read, write and work on his tennis swing would seem reasonable. But for Chief Justice William H. Rehnquist, the prospect of retirement is fraught with political consequences.

Retirement rumors have swirled around Rehnquist for several years, and the judge is keeping his thoughts on the subject to himself. But age, accomplishment and politics may combine to persuade Rehnquist to make his exit, possibly after the upcoming term ends next June, say Supreme Court observers.

"Chief Justice Rehnquist's interests beyond the court are varied and dear to him, and I wouldn't be surprised if in the not-distant future he decided to pursue those interests," said Charles Cooper, a Washington lawyer who once served as a law clerk to Rehnquist.

Rehnquist has passed his 30th anniversary on the court, more than half that time spent as chief justice. He has participated in an extraordinary range of issues, from abortion to school prayer to the 2000 presidential election.

Once a lone ranger on the right, filing fierce dissents to his colleagues' often liberal rulings, Rehnquist is now the arbiter of the court's increasingly conservative outlook. He could leave safe in the knowledge that much of the court now thinks as he does, lawyers said.

Established in history

"If the chief justice ends his term on the court this year he will already have established himself as one of the three most important chief justices in history," said Walter Dellinger, a former chief Supreme Court lawyer for the Clinton administration.

Rehnquist would share that honor with 19th century legend John Marshall and Earl Warren, architect of the court's civil rights-era rulings, Dellinger said.

Politics can be a major consideration for any justice contemplating retirement.

Justices have generally preferred to leave when a president of his own political party occupies the White House. Rehnquist was active in Republican politics before he was named to the court by Richard Nixon. He was elevated to chief justice by Ronald Reagan.

Justices also keep an eye on the presidential election calendar. Bush is expected to run for re-election in 2004, and the ideological makeup of the Supreme Court will probably be an election-year issue.

Timing matters

"No one wants to resign in the middle of a presidential election," Dellinger said. That makes a resignation more likely when the court completes its upcoming term, lawyers said.

Presumably, a Republican justice would want to give his or her party maximum advantage in choosing a replacement, lawyers said. Also, no justice would want to hamstring the work of the court by creating a vacancy that would be hard to fill because of election-year politics.

A nominee could be held up in the Senate for months, leaving the court with only eight members. Rulings split by a 4-4 vote have no effect; the decision of a lower court stands in those cases.

In this year's congressional elections, Republicans have a chance to reclaim control of the Senate. Rehnquist may feel more comfortable leaving next summer if he knows his replacement is not likely to be caught between a Republican White House and a Democratic-controlled Senate, lawyers said.

"If Republicans take control, I think that at least marginally would increase the chances," said Emory University law professor David Garrow, who has written extensively about the Supreme Court. "In reverse, the hypothetical is if the Democrats maintain control of the Senate, that at least at the margin reduces the chances of anybody leaving."

If he bows out, Rehnquist will end a period of historic stability on the court. The same nine justices have served together since 1994, the longest period without a death or retirement since the early 19th century.

Justice Sandra Day O'Connor, named to the court by Reagan in 1981, is also the subject of recurring retirement rumors. Other speculation focuses on Justice John Paul Stevens, named to the court by Republican Gerald Ford but now a stalwart of the court's liberal-leaning wing.

Neither has indicated an intention to leave soon, and most of the speculation focuses on their ages -- O'Connor is 72 and Stevens a decade older -- and their longevity on the court.

The White House has a list of possible replacements but won't say much about them. Many of the candidates are likely to be federal judges well known in legal and conservative circles but far from household names. At the head of the list is said to be the man in charge of making the list -- White House Counsel Alberto Gonzales.