JERUSALEM -- Israeli Prime Minister Ariel Sharon is taking a bold gamble in letting 200,000 members of his Likud Party have the final say on a plan to withdraw from the Gaza Strip.

If Sharon wins and leads Israel out of Gaza, he could earn a place in history as one of the nation's great prime ministers. If he loses, he may have to resign.

His tight timetable for getting the Gaza plan approved suggests a sudden urgency after more than three years of political indecision and bloody deadlock with the Palestinians.

On April 14, Sharon will seek President Bush's blessing in a Washington meeting. The Likud referendum is to be held in mid-May, followed immediately by a vote in the Israeli Cabinet and perhaps also in parliament.

Few would have predicted that Sharon -- the political patron of the settler movement -- would become the first prime minister to try to uproot some of their communities. Sharon says he's had a change of heart and believes a limited pullout is in Israel's best interest.

Sharon's critics believe his Gaza pullout plan is tied to the attorney general's plan to decide by the end of May on whether to indict Sharon in a bribery case. They say that the prime minister is trying to create an atmosphere in which it becomes increasingly difficult for Attorney General Meni Mazuz to indict him.

Victory not guaranteed

The Likud poll "creates pressure on the attorney general ... not to sever any historic move that Sharon says he intends to implement," columnist Hannah Kim wrote in the Haaretz daily Friday.

Even if Mazuz decides not to file charges, Sharon could be under pressure to step down if he loses the Likud vote.

"He would be more than a lame duck," analyst Hanan Crystal said. "If this is his historic move and he cannot persuade his party, he would have to resign."

Pollsters caution that a Sharon victory is not guaranteed. A survey of 507 Likud members this week indicated 51 percent are in favor of a Gaza withdrawal and 36 percent are opposed, with a margin of error of 4.4 percentage points.

Sharon has "an advantage, but it's not big enough," said Mina Zemach of the Dahaf polling institute. "It's not in his pocket."

The Jewish settlement movement, as well as renegade Likud Cabinet ministers and legislators, have launched an anti-withdrawal campaign among Likud members.

Settlers say they plan to contact all party members personally, calling them or visiting them at home. By mid-April, the settlement movement will make an emotional appeal in the form of a video featuring Gaza settlers.

"We want people to know that this means uprooting 8,000 decent people," said Shaul Goldstein, deputy chairman of the Yesha Settlers' Council.

Despite the risks, Sharon is confident he can win the Likud vote, his public relations adviser Eyal Arad said. "We wouldn't go into it if we didn't think we had a chance," Arad said.

Clever tactical move

Arad is counting on Sharon's personal appeal. He said the prime minister will deliver speeches and give interviews at every opportunity to sway Likud hard-liners. A Bush endorsement would help, Sharon aides said.

The prime minister began campaigning this week, defending the Gaza plan in interviews with three newspapers. Sharon's main message is that Israel would only come under growing international pressure to give up more land if it does nothing.

A date for the referendum -- unprecedented in Israel's history -- has not yet been set. It has to be held within three weeks after Sharon formally requests it, immediately after his return from Washington in mid-April.

Sharon advisers said it would likely take place in mid-May.

Sharon's timeline also takes into account the expected departure of two ultra-nationalist coalition partners, the National Religious Party and the National Union, in protest over a Cabinet approval of the Gaza plan.

The moderate opposition Labor Party appears to be waiting in the wings, though party leaders deny reports they've already divvied up the Cabinet posts with Sharon. Labor was Sharon's junior coalition partner from 2001 until late 2002, when it quit in a dispute over settlement funding.

Labor leaders say they won't join Sharon unless he is cleared of corruption. With the Cabinet expected to vote just before Mazuz makes his ruling, uncertainty over the composition of Israel's next government might last only a few days.

Even if the attorney general decides to indict or Likud rejects the Gaza plan, Sharon may resist resignation as long as possible. He has said he intends to stay in office until his term ends in 2007.

Yoel Marcus, a veteran Haaretz columnist and longtime Sharon critic, wrote that in the race to get the Gaza plan approved before the attorney general rules, he is rooting for the prime minister.

"At the moment, I don't see anyone else who could pull such a thing off, apart from him," Marcus wrote.