The results of the referendum, announced late on Sunday night, showed that around 60% of Likud party members voted against the plan, with less than 40% supporting it.
The very idea of holding a referendum within the Likud over the plan was devised by Sharon himself, who apparently took a "yes-vote" for granted.
Losing the ballot seems to suggest the PM underestimated the power of his opponents within a party that has been drifting even further to the extreme right.
According to Uri Avnery, a veteran Israeli peace activist and political commentator, Sharon is already finding himself in a tough spot.
"He is now in an impossible situation. He has lost the confidence of his own party and it will be difficult for him to recover his stature."
Avnery believes that Sharon has incurred "this fiasco" upon himself because "he has never been serious about the plan".
"Look, he didn’t present a real plan, there was no timetable, no details about the borders, no details about subsequent steps, the whole thing was incoherent and too general."
Asked what he thought Sharon would do now, having lost the referendum, the former Knesset member said Sharon was now "very dangerous".
Israeli analyst claims there was
never a real plan to vote on
"He is a wounded animal now. In ordinary times, he was dangerous and unpredictable. Now he is even more dangerous and more unpredictable."
Avnery hinted that Sharon might resort to assassinating Palestinian Authority Leader Yasir Arafat or carry out some theatrical operations against the Palestinians in order to appease the more jingoistic and extremist segments in his party.
However, he believes that no matter what Sharon does, it will not be easy for him.
"You see the basic situation in Israel today is that we have highly motivated and highly dedicated groups who reject peace or compromise with the Palestinians ... as a matter of principle.
"On the other hand, much of the Israeli public is apathetic and unwilling to put up a serious challenge to this fanatic anti-peace camp."
With his party badly divided, Sharon is unlikely to soon find an exit to political safety.
Indeed, Sharon’s ostensible insistence on carrying on with the disengagement plan, despite its rejection by the Likud, would probably further divide the party and might even lead to its disintegration.
"He is a wounded animal now. In ordinary times, he was dangerous and unpredictable. Now he is even more dangerous and more unpredictable"
Israeli peace activist and political commentator
On the other hand, if he abandons the Gaza plan, he would also further embarrass the US - Israel’s guardian-ally.
More to the point, Sharon would be effectively succumbing to the hawkish elements within the Likud and the religious-Zionist camp that espouse the ideology of "Erez Yisrael Hashlema" or "the Greater Land of Israel", which includes Israel proper, the West Bank, East Jerusalem, Gaza and the Golan heights.
Hence, the dilemma.
Leader without a party
Some Israeli analysts are already calling Sharon "a leader without a party".
According to Aluf Benn, a political analyst from the Ha’aretz newspaper, Sharon has buried himself and will find it extremely difficult to escape by choosing to bypass his party over withdrawal.
On the other hand, not abandoning the plan would likely corrode Sharon’s credibility in American eyes.
"This is the second time the US has been embarrassed by an Israeli Prime Minister who harnessed American support for a courageous initiative.
"President George Bush put his prestige on the line at home and in the Arab world by throwing his weight behind Sharon ... just as President Bill Clinton did for Barak," says Benn.
Likud vote makes it inevitable
more people will lose lives in Gaza
Another prominent Israeli analyst, Akiva Eldar, places much of the blame on Likud itself.
Writing in Ha’aretz on Monday, Eldar said that peace forces in Israel, which advocate negotiations with the elected representatives of the Palestinians, ought to free themselves from the illusion that the Likud could make peace with the Palestinians.
"The disengagement referendum ought to disengage the peace process once and for all from the delusion that 'only the Likud can'," wrote Benn, alluding to the famous Likud election jingle "Rak Ha’liku Yakhol" or "Only the Likud can."
"Maybe the Likud can, but obviously, it doesn’t want to."
Meanwhile, Palestinian analysts and some PA officials have voiced ambivalent reactions with a modicum of satisfaction at the outcome of the referendum within the Likud.
Palestinian political analyst Hani al-Masri termed the result of the referendum "good news" for the Palestinians.
"The so-called disengagement plan is actually aimed at liquidating the Palestinian issue. It is a very dangerous plan. We should be happy that it didn’t pass."
Al-Masri believes that not only Sharon but also the entire Israeli right has reached a dead end.
"Look, this [referendum outcome] shows that the Zionist right has failed on the two fronts, making peace and imposing a solution on the Palestinians by force."
And like Avnery, al-Masri believes that a weak Sharon is also a very dangerous one.
"I think he could carry out some atrocities in an effort to reunify the Likud around him.
"But this won’t solve the basic problem in the long run," he told Aljazeera.net.
Sharon himself refused to say what steps he would take following Sunday’s referendum.