The showdown Knesset vote next week over the Israeli government’s proposed 2005 budget, which by all rights should have been held months ago (the government has been operating since January 1 on the budgetary equivalent of automatic pilot), has been rightly billed as a vote of confidence in Ariel Sharon’s Gaza disengagement plan. And yet the widely held assumption that if the vote goes against Mr. Sharon, his plan will have been dealt a fatal blow, is unwarranted. On the contrary: A defeat in the Knesset might be just what he needs to rectify his mistakes and carry disengagement out as smoothly as possible.

These mistakes were two: holding the wrong referendum on the disengagement plan – and not holding the right one.

The wrong one was the one, conducted as an intraparty ballot of Likud members last May, in which Mr. Sharon was badly beaten. The right one would have been a nationwide plebiscite. It never took place partly because it would have been difficult to organize, partly because it would have involved Knesset legislation for which there was not an assured majority, and partly because Mr. Sharon, smarting from his loss in May, was afraid to try his luck again.

He shouldn’t have been. Every single public opinion poll has shown that, put to a nationwide vote, disengagement from Gaza would be approved by a huge margin. It is what the people of Israel clearly want. It is thus ironic that it is the plan’s opponents who have been pressing for a national referendum and its proponents who have refused to hear of it.

True, many of the opponents of disengagement cynically regard such a procedure as merely a way of stalling for time. Yet they should have had their bluff called – and others, especially in the more moderate circles of the settler movement and its supporters, are sincere in their promise to honor a referendum’s outcome and in their observation that a heavily pro-disengagement result would help keep anti-disengagement demonstrations this spring and summer from turning extreme and violent. Some have pleaded with Mr. Sharon to avoid the mistake made by Yitzhak Rabin in going to Oslo in 1993, when his sudden reversal of policy, executed without asking the public to renew his mandate, cost him his legitimacy in the eyes of many Israelis.

Of course, as has been repeatedly pointed out by disengagement’s proponents, the prime minister is under no obligation to get the nation’s approval for it. All he needs is the parliamentary majority that he may fall short of by the narrowest of margins in next week’s budget vote because a third of his own Likud Knesset faction is poised to vote against him. If the budget fails to pass, he will be forced by Israeli law to resign, and new parliamentary elections will have to be held.

And yet this might be the best thing for disengagement that could happen, since these elections would be the equivalent of the national referendum that should have been held, and Mr. Sharon would win them handily.

This does not mean that he would have an easy time of it. Before winning an election, he would have to get on the ballot, and to do so again as head of the Likud would involve campaigning for the party’s nomination against raucous opposition. Yet it is a campaign he would certainly win, if only because every survey shows him far outpolling his closest contender, Likud Finance Minister Benjamin Netanyahu, in a national election.

Even those Likud politicians who are against disengagement know how to count. A prime minister who withdraws from Gaza but can be returned to office while putting 40 or 45 Likud members into the next Knesset as part of his electoral list is worth more to them than an unelectable one who is against disengagement.

Indeed, the party fight that would precede Mr. Sharon’s renomination would be an ideal opportunity for him to clean house. He might manage to dump some of his more vocal Likud Knesset critics from the party’s list while bringing others to heel, forcing them to drop their opposition to disengagement in return for another term in the Knesset. Here, too, he would have the whip hand in the bitter fight that would ensue.

Nor would any of this have to delay disengagement itself. If the government falls next week, elections will be held at the end of June. The actual withdrawal of settlers and the army from the Gaza Strip, on the other hand, is not planned to commence before July. Between now and then, Mr. Sharon would remain at the head of a caretaker government that could go ahead with planning the withdrawal and putting its last details in place. He would be re-elected just in time to carry it out on schedule.

Would Mr. Sharon actually prefer to lose next week’s budget vote so that events could take such a turn? Probably not; he’s had enough excitement as it is these past months and isn’t looking, between now and July, for any more that isn’t absolutely necessary. Yet he has no reason to be afraid of such a development, either. It’s the opponents of disengagement who do – and they know it. That’s why it wouldn’t be surprising if, at the last moment, they discreetly help Mr. Sharon to win the budget vote.

Mr. Halkin is a contributing editor of The New York Sun.