Ailing Chief Justice William H. Rehnquist (search) will be absent from the bench when the Supreme Court returns for the second half of its term next week, the court announced Friday.

The 80-year-old Rehnquist, battling thyroid cancer, plans to skip the two-week cycle of oral arguments that starts Tuesday, court spokeswoman Kathy Arberg said. He will continue reading transcripts of the arguments and voting on decisions, she said.

Rehnquist has been working mainly from home since Oct. 22, when he was hospitalized and then underwent a tracheotomy to help him breathe. He made his first public appearance last month at the presidential inauguration, appearing fragile as he delivered the oath of office.

Rehnquist's illness has led to speculation that he will step down, giving the court its first opening since 1994. While such an announcement could come at any time, justices typically wait until the term ends in June to leave to avoid an extended vacancy and the possibility of 4-4 votes on cases.

The court resumes its term with two weeks of arguments featuring contentious issues such as property rights and display of the Ten Commandments (search) in government buildings. Some court watchers had suggested Rehnquist might try to sit for those arguments because he has a special interest in religious freedom and eminent domain cases.

He has reduced his workload during his cancer treatment. He is not participating in decisions from the dozen cases heard in November unless the remaining eight justices are deadlocked. He intends to take part in the December and January cases, relying on briefs and transcripts of the arguments.

Outside medical experts have said that, based on his treatment of chemotherapy and radiation, he may have an extremely aggressive kind of thyroid cancer. Over time, that cancer would make it more difficult for Rehnquist to swallow or talk.

"The treatment was supposed to shrink the tumor and improve, rather than deteriorate, the voice quality," said Dr. Yosef Krespi (search), a cancer expert at St. Luke's-Roosevelt Hospital in New York. "The fact that he can't carry oral arguments tells me the tumor is poorly responding."

In the court's announcement Friday, Arberg cited Rehnquist's prior concerns about returning to the bench due to "continuing secretions caused by his tracheotomy and radiation therapy."

Rehnquist celebrated his 33rd anniversary on the court last month and has been chief justice since 1986.