ASHINGTON, Feb. 21 - When the Supreme Court resumes its term on Tuesday, Chief Justice William H. Rehnquist will again be absent from the bench because of his illness. Although he is not bedridden and has been regularly attending the justices' private conferences, his empty black leather chair will certainly set off a new round of speculation and chatter about his tenure on the court.

But for senior White House officials, as well as a handful of others who follow the court closely, a working assumption about what is going to happen has already taken shape. The strong expectation, senior administration officials and others said, is that Chief Justice Rehnquist is making his best effort to serve out the remainder of the term that ends in June before resigning. And the only question, they say, is whether the 80-year-old chief justice, who is suffering from thyroid cancer and the effects of his treatment, will be able to do so.

The people who said that this was the assumption in the White House included senior administration officials, senior Congressional officials and people who have been consulted by senior White House officials.

Top White House officials have discussed the situation, one of those people said, and have concluded that they will have to be ready for President Bush to make known his intentions for replacing the chief justice no later than June but possibly sooner. They have prepared ever-narrowing lists of candidates to be nominated for the court, one official said.

"The thinking, clearly, is that the chief will retire in June," said a person who has participated in these discussions. "The question is, of course, is whether he will be able to endure until then."

No one, from the most high-level administration officials to those on the periphery of the discussions, agreed to be quoted by name, both because the discussions are confidential and, just as important, because it is considered unseemly to discuss someone's serious illness.

Moreover, it is improbable that the expectations about Chief Justice Rehnquist stem from any direct signal from him. Rather, it is the combination of several factors, including his age and illness and his statement years ago that he well understood the tradition in which justices try to leave when the White House is occupied by a president of the same party as the one who nominated that justice. He was first named to the court by President Richard M. Nixon.

The officials who spoke about the expectations of Chief Justice Rehnquist's retirement, along with many other lawyers, noted how disruptive it was for a justice to leave in midterm, supporting the notion that the chief justice is hoping to get to the natural break in June, the time when most justices choose to step down..

The officials said that among the candidates being considered most seriously for nomination to the Supreme Court are a handful of federal appellate judges. Included on the list are Judges Michael W. McConnell of the United States Court of Appeals for the 10th Circuit, John G. Roberts of the United States Court of Appeals for the District of Columbia and J. Harvie Wilkinson III and J. Michael Luttig, both of the United States Court of Appeals for the Fourth Circuit. Another possible candidate is Judge Samuel A. Alito of the United States Court of Appeals for the Third Circuit, who sits in Newark.

If Chief Justice Rehnquist were to be the first of the current justices to leave the court, Mr. Bush would have to decide whether to nominate a new chief justice or elevate one of the sitting associate justices and nominate someone to fill the vacancy that would create.

The potential outside nominees are all judicial conservatives of strong, if varying, degrees. One outside adviser suggested that Judge McConnell had risen in the White House's handicapping because, among other things, he had been supported in his nomination to the appeals court by dozens of liberal law professors.

Before joining the bench, Judge McConnell was a law professor who was well known for his erudite criticism of legalized abortion. When he encountered opposition during his nomination to the appeals court, some 200 law professors, ranging across the ideological spectrum, signed a petition supporting his confirmation.

In announcing that Chief Justice Rehnquist would not sit during the two weeks of oral argument, a court spokeswoman attributed his absence to the same reasons cited on Jan. 7 for his missing arguments that month. The reason given then was difficulty with "continuing secretions caused by his tracheotomy and radiation therapy."

Doctors not associated with his case said that appeared to mean that Chief Justice Rehnquist required regular suctioning to remove the secretions and so could not remain unattended for hours at a time. It also suggested he might be taking frequent breaks from the private justices' conference for the procedure, something that would be impractical during public arguments that last an hour at a time.

He has announced that he will participate in the decisions on the cases for which he will not attend the arguments by reading the briefs and reviewing the transcripts of the public sessions.

Chief Justice Rehnquist last appeared in public on Jan. 20 to swear in Mr. Bush, fulfilling a promise he had made late last year. He remained in public on the platform for only 13 minutes.