JERUSALEM (CNN) -- Doctors at Hadassah Hospital replaced the breathing tube of Israeli Prime Minister Ariel Sharon early Wednesday, in a procedure a hospital spokesman called "successful."

According to the spokesman, the tube was changed due to a technical problem. He said the prime minister's condition remains "serious and stable."

The procedure came after Sharon's family on Monday said the prime minister moved his eyelids, according to a family statement.

On Sunday, Sharon underwent a tracheotomy to help wean him off a respirator. A tracheotomy is a surgical incision of the trachea through the neck to make an opening for breathing. (Diagram)

Sharon, 77, has been comatose since the January 4 stroke that resulted in brain hemorrhaging.

Sharon's aides said the prime minister had opened his eyes, according to some Israeli Web sites, but the statement from Hadassah Hospital denied his eyes had fully opened.

The medical significance of the eyelid movement was unknown, the statement said.

Since the stroke, doctors have performed 13 hours of surgery on Sharon to reduce bleeding in his brain. Last week physicians began slowly lowering Sharon's dosage of anesthesia to bring him out of a medically induced coma.

Sharon's stroke sent shock waves through Israel's fragile political landscape at a sensitive time in Mideast events, just weeks before an Israeli parliamentary vote on March 28 and Palestinian elections on January 25.

He stopped receiving any sedation Saturday morning, Hadassah Hospital said in a statement. That he hasn't regained consciousness has drawn increasing concern among his doctors. (Full story)

"The condition of the prime minister continues to be critical and stable," the hospital said in an earlier statement.

Doctors said last week that Sharon had shown slight improvement from various neurological exams, and had moved his right and left hand along with his right leg. The movement on the left side is significant because the left side of the body is controlled by the right side of the brain, which was damaged by the stroke.

Last Friday, a hospital statement said Sharon underwent a brain scan that revealed he no longer needed a tube to drain excess blood from his brain, and the tube was removed. An intravenous drip also was inserted into his arm to reduce his chances of infection.

His recovery could take months, said one of his physicians, Dr. Jose Cohen. Another, Dr. Felix Umansky, cautioned that "we cannot say that he is out of danger."

During Sharon's hospitalization, his powers as prime minister were transferred to Ehud Olmert, his longtime loyalist and a former Jerusalem mayor.

On Monday, Kadima party legislators elected Olmert as interim party leader during the group's first meeting since Sharon's hospitalization, a statement from the group said.

Sharon founded Kadima in November after leaving the Likud party, which included members who strongly opposed his plan to withdraw Israeli troops and setters from Gaza and parts of the West Bank.

Before his stroke, polls had shown that with Sharon at the helm, Kadima would win the largest block of seats in Israel's parliament, the Knesset, in the March elections, making it likely he would remain prime minister.

With Palestinian elections also approaching, Israel's Cabinet on Sunday unanimously approved a proposal allowing Palestinian residents to vote at polling places in East Jerusalem. The approval could help end a Palestinian threat to postpone the election.

The Cabinet said Hamas, a Palestinian Islamic fundamentalist group that calls for Israel's destruction, will not be allowed to campaign in East Jerusalem