The "disengagement plan" had been expected to squeak through the Cabinet on Sunday after Sharon fired two ministers adamantly opposed to it.
However, Judge Edmond Levy asked Sharon to delay the vote for two days to give the court time to rule on the ministers' dismissals. Levy gave Sharon until Sunday afternoon to decide whether to follow his recommendation or a three-judge panel would issue a binding ruling on whether to delay the vote.
The Cabinet had been expected to narrowly approve Sharon's plan to evacuate 21 smaller Jewish settlements in Gaza and four in the occupied West Bank in a vote scheduled to take place after 3:30pm (12:30GMT).
Sharon's plan includes trading the Gaza settlements for control of the main settlement blocs in the occupied West Bank where most of the 230,000 settlers live.
Only 7,500 settlers live in the Gaza Strip blocs.
Jewish settlements are illegal under international law, a stance not recognised by Israel.
Sharon has been a champion of settlers and once called on them to "seize the hilltops".
The slim 11-10 Cabinet majority was only secured after Sharon fired two ministers from the hawkish National Union Party on Friday. However, those dismissals were challenged in several court appeals on Sunday.
Avigdor Lieberman (R) and Benny
Elon were fired to secure majority
Sharon says he hopes to complete the evacuations by the end of 2005.
Even if the vote is held Sunday, the Cabinet will only be asked to approve a statement supporting the "disengagement plan" in principle. The ministers would have to vote again, probably in about six months, before any evacuation takes place.
The fallout from the dispute over the plan threatens Sharon's increasingly tenuous grip on power.
Even a preliminary vote could break apart the hardline coalition, with the pro-settler National Religious Party threatening to bolt, leaving Sharon with a minority government.
The plan also requires parliamentary approval. The opposition Labor Party said it would support Sharon's plan in parliament, but would not join the coalition.
Likud's Finance Minister Benjamin Netanyahu, Foreign Minister Silvan Shalom and Education Minister Limor Livnat held last-minute talks to find a compromise they say would allow them to support the plan.
Negotiations are focused on funding for building projects in Gaza settlements slated for evacuation. The three ministers oppose freezing construction, while Sharon has said it would be "absurd" to continue funneling funds to the Gaza communities.
Efforts to get the vote through the Cabinet were fitful and turned into a near farce on Friday when one of the sacked ministers, Benny Elon, went into hiding to avoid being served with his dismissal notice. Under Israeli law, the dismissals only take effect 48 hours after delivery of the notice.
Elon eventually received the written dismissal but Attorney General Meni Mazuz ruled he would not be allowed to vote after 3:30 pm (1230 GMT) on Sunday because the notice had been faxed to his office on Friday.