By James Reynolds
BBC News, Jerusalem
Israel collectively waits to find out whether or not its prime minister will recover from his stroke.
Sharon's health crisis dominates public debate
Driving back from the hospital late last night at about 0200, two men in the car next to me waved at me to wind down my window at some traffic lights.
They asked "Have you heard any more information about Sharon?".
It has been that kind of day and night, as everyone eagerly awaits information about his health.
There have been waves of rumours spreading about Mr Sharon's death, in a repeat of the time before Yasser Arafat's demise when there were persistent rumours of his passing days before he actually died.
Hadassah hospital is trying to prevent these rumours from escalating by making sure there is a regular supply of official information.
They have been giving regular on-camera bulletins in both English and Hebrew every two or three hours.
While Jerusalem is shrouded in an air of uncertainty, the mood is certainly not of shock or surprise.
Ever since Mr Sharon's first stroke almost three weeks ago, people have been preparing themselves for his health worsening.
There is a feeling, if not of orphanhood, then of bereavement amongst Israelis.
They know that, even if he recovers, he is unlikely to be able to carry on with politics.
No-one knows whether Mr Olmert, if he is to stay, will attract the same support that Mr Sharon fostered
He commands the Israeli centre ground in a way that no other politician has, perhaps since the days of David Ben-Gurion, the first Israeli prime minister.
Mr Sharon has attracted the support of left-wingers who do not want to rule over Palestinians and right-wingers who do not want to negotiate with them, as well as the backing of the bulk of normal Israelis who are fed up with suicide bombings and who want a tough military presence.
Not only does he provide policies, he provides personality.
As someone who for 60 years fought in all of Israel's wars, he is considered the ultimate 'Mr Security'.
If they do not have this ultimate 'Mr Security' then a lot of Israelis will feel not only bereft, but insecure.
Although the news broke late last night, it is on the covers of a number of papers' last editions.
For Israeli politicians, Sharon will be a hard act to follow
Haaretz says 'Sharon fighting for life after stroke', as do a number of others.
All of them are talking about the fact that Ehud Olmert, Mr Sharon's deputy, will be taking over for the foreseeable future.
But beyond that there is a huge question mark.
No-one knows whether Mr Olmert, if he is to stay, will attract the same support that Mr Sharon fostered.
No-one knows whether Benjamin Netanyahu on the right-wing or Amir Peretz on the left-wing will be able to either, such was the strength of Mr Sharon's personality.
If this does to prove to be the demise of Ariel Sharon, it is a demise which has been signposted over the last few weeks by his health problems - unlike the sudden death of their prime minister when Yitzhak Rabin was assassinated 10 years ago.
The prime minister's death will not come in the middle of a peace process like Rabin's did, so while there will be uncertainty and a rearranging of the furniture of Israeli politics, Israelis have been through this before.
As events reach their climax, the turmoil is unlikely to be anything new in Israeli politics which, by definition, is always in confusion, crisis and argument.