Sharon, 85, who has been comatose for eight years after suffering a stroke, has been in a rapidly deteriorating state after contracting a severe blood infection.
"I can't say I'm optimistic this morning, and I'm possibly even more pessimistic than I was before," Ze'ev Rotstein, the head of the Sheba Medical Center at Tel Hashomer where Sharon is being treated, told the Jerusalem Post.
"He is comfortable at this time. To the best of our understanding he is not suffering, such that we do not have to take any action to prevent him suffering," Rotstein said.
When asked whether Sharon may be in his last days, Rotstein said: "I personally feel so."
Saturday marked eight years since the stroke that ended Sharon's political career. Sharon's former bureau chief Dov Weisglass said the former prime minister was particularly missed on that day.
"The Middle East changed eight years ago because we lost a leader who knew how to make decisions," said former Kadima Knesset member Shai Hermesh, a close friend of the Sharon family. "Now I am worried world leaders won't come to his funeral like they would have had he died eight years ago."