William H. Rehnquist, chief justice of the U.S. Supreme court who has cancer, has been hospitalized with a fever, a spokeswoman said Wednesday. Rehnquist was taken by ambulance to an Arlington, Va., hospital Tuesday night and was admitted for observation and tests, Supreme Court spokeswoman Kathy Arberg said, according to AP. There was no immediate word on his condition Wednesday afternoon. Rehnquist, 80 and ill with thyroid cancer, has been the subject of intense speculation about whether he planned to retire. Justice Sandra Day O'Connor, 75, announced earlier this month that she will be leaving the nine-member court, which is the final arbiter of whether U.S. laws are acceptable under the Constitution. The chief justice had been coming to the court daily but did not show up Wednesday morning. Court officials initially declined to say why he was absent or explain unusual happenings at Rehnquist's suburban home. Arberg eventually issued a two-sentence statement saying Rehnquist was hospitalized for a fever and was undergoing tests. It was the second time in less than four months that an ambulance had taken Rehnquist to a hospital. In March, he was taken with breathing problems but did not stay overnight.