Jerusalem ? Israeli Prime Minister Ariel Sharon appeared to have surmounted the last major legislative hurdle to his Gaza withdrawal plan Saturday when a key opposition party announced it would vote in favor of his proposed national budget in parliament this week.

Tommy Lapid, the leader of the centrist Shinui Party, announced his support of the budget after a meeting with Sharon on Saturday night.

The announcement by Shinui, with 15 seats in the Israeli parliament, or Knesset, ends a weeks-long political drama as Sharon has scrambled to assemble a Knesset plurality for his budget.

Under Israeli law, failure to pass a 2005 spending plan by Thursday automatically would dissolve the parliament and force early elections. That probably would have delayed, or even scuttled, the pullout, also known as disengagement.

Shinui had threatened to vote against the budget, although it strongly supports the Gaza pullout. The party’s support ensures that Sharon can win passage of the spending plan without the help of leftist and Arab lawmakers who favor the withdrawal but oppose the budget on fiscal grounds.

“The last parliamentary hurdle to the disengagement had been removed,” Sharon spokesman Raanan Gissin said. “Now it’s a clear road to the disengagement.”

Gissin said Sharon promised Lapid that the budget would allocate about $160 million more for education and other causes favored by Shinui.

The budget is to be debated in the Knesset this week, with a vote planned for Tuesday or Wednesday. Until Saturday’s announcement by Shunui, Sharon remained a few votes shy of the plurality needed for passage in the 120-seat Knesset.

Although most analysts had predicted that Sharon would find the votes, the prime minister’s aides warned in recent days that the outcome was far from certain, suggesting he might be forced to call early elections.

By law, national elections would have to be held in 90 days — just weeks before the evacuation is due to begin July 20.

The pullout calls for withdrawal of Jewish settlers and soldiers from all 21 Israeli settlements in the Gaza Strip and four others in the northern West Bank.

The budget vote offered opponents of the plan, including some members of Sharon’s own Likud Party, their best remaining chance to stymie the withdrawal, which many view as forcible expulsion of Jews from land that is their biblical birthright.

A separate measure calling for a national referendum on the withdrawal is also to be voted upon in the Knesset early this week, but supporters appear well short of the votes to get it passed.