Three of the four Likud party ministers in Israel's government have resigned from the cabinet after party leader Binyamin Netanyahu ordered them to go.
Netanyahu took over from Sharon as Likud leader late last year
Foreign Minister Silvan Shalom did not resign, but is expected to quit at the cabinet meeting on Sunday.
The resignations had been planned, but were postponed after Prime Minister Ariel Sharon had a stroke last week.
Doctors at Jerusalem's Hadassah hospital say Mr Sharon will undergo a routine brain scan on Thursday.
They say the premier's condition remains critical but stable.
The 77-year-old is on a low dose of the sedatives that have kept him in a coma.
However, medical sources told the Reuters news agency that doctors could end Mr Sharon's sedation on Thursday, in order to be able to assess the extent of any neurological damage.
The resignations of the ministers will come into effect in 48 hours.
"Likud chairman Binyamin has handed over the letters of resignation to the cabinet secretariat in Jerusalem," a Likud statement said.
Earlier, reports said the ministers had refused Mr Netanyahu's order to resign immediately, saying they would quit on Sunday.
ARIEL SHARON'S HEALTH
Sharon suffers minor stroke on 18 December 2005
Doctors discover small hole in heart, schedule operation for 5 January
Sharon rushed to hospital one day before scheduled surgery with major stroke
Undergoes two operations overnight on 4/5 January, followed by third on 6 January
Mr Netanyahu ordered Mr Shalom, Agriculture Minister Yisrael Katz, Education Minister Limor Livnat and Health Minister Danny Naveh to submit their letters of resignation to acting Prime Minister Ehud Olmert earlier on Thursday.
"The Likud cannot present itself as an alternative if it remains in the government and continues to implement its policies," the party said in statement on Wednesday.
The Labour Party declared its campaign for the 28 March general election to be up and running on Wednesday, as opinion polls suggested that Mr Sharon's new ruling party, Kadima, could still win the election even if he was not at the helm.
Likud is meeting on Thursday to decide its list of candidates.