Shinui leaders Yosef Lapid and Avraham Poraz told Prime Minister Ariel Sharon on Saturday night that they would back the 2005 state budget in the Knesset this week, assuring that it will pass and that the government will not fall before it the planned execution of the disengagement plan this summer.

If the budget bill is not passed by the Knesset, the government would fall and new elections would be called, postponing the disengagement plan to 2006.

At a three-hour meeting Saturday at Sharon's Sycamore Ranch in the Negev, Lapid and Poraz agreed to back the budget in exchange for a budget transfer of NIS 700 million. The money is slated to go to higher education, recently released conscripts and reserves soldiers, cultural institutions and environmental causes.

After the meeting, Lapid said that he had decided to support the budget in order to save the disengagement plan.

But it still remains unclear whether Shinui will support the budget as a united front, as MK Hemi Doron told Israel Radio Sunday that he was opposed to the Lapid-Sharon agreement, and would weight his vote on the issue.

Interior Minister Ophir Pines-Paz (Labor) said he would oppose any effort to cut his ministry's budget in order to accommodate promises made to Shinui as part of the deal forged between Sharon and Lapid.

How the funds will be divided will be determined Sunday morning at a meeting between Cabinet Secretary Yisrael Maimon, director general of the Prime Minister's Office Ilan Cohen, budgets director at the Finance Ministry Kobi Haber and Shinui MKs Poraz, Ehud Ratzabi and Ronnie Brizon.

Sharon said Saturday's meeting with Shinui leaders was "good" and said Shinui's budgetary demands "serve important causes. There were no religious issues here."

"The budget will pass now," Sharon told Haaretz, and predicted the referendum bill will not be approved by the Knesset on Monday. "My conduct was calm throughout," Sharon said.

Before the agreement hammered out Saturday, Lapid and Poraz reiterated their demand that Sharon promote the civil marriage bill. They did not introduce their demands for forming a secular coalition and canceling the agreement granting NIS 290 million to United Torah Judaism.

Sharon refused to help promote the civil marriage bill, claiming objections from UTJ and many Likud members. Cabinet Secretary Maimon, who was present at the meeting, expressed concern that supporting the bill would create upheaval in the Likud, fomenting support in the faction for the referendum bill to be voted on Monday.

Once the civil marriage issue was definitively off the table, Lapid and Poraz withdrew to another room for consultation. Upon returning, they said they would remove their opposition to the budget in return for a NIS 700 million grant. Sharon immediately agreed and informed Finance Minister Benjamin Netanyahu.

Netanyahu's office announced Saturday that he welcomes the agreement with Shinui, which guarantees the budget will pass, and that "any sum given to Shinui will be cut from the budgets of all government ministries, since the budget framework for 2005 will not be broken."

Treasury officials said the government will convene next Sunday, in keeping with a previous agreement between Sharon and Netanyahu, to discuss ways of balancing the budget, once it has been approved by the Knesset this week.

"We concluded that the disengagement is in real jeopardy, and we cannot endanger it. Only after we were convinced by Sharon that he cannot meet our demands on issues of religion and state did we agree to accept money in return for our support, and to transfer it to sectors affiliated with us," Lapid said.

Lapid added that he knows the decision will meet with harsh criticism, but he is prepared to weather that so as not to topple the disengagement and to help students, soldiers, arts and sciences.

Shinui's support assures the budget a decisive majority of at least 67 MKs, removing the threat to the government. Nonetheless, Sharon will continue striving to increase the majority for the budget. He will meet today with Yahad chairman Yossi Beilin, who had made it clear recently that his party would not permit the government to fall over the budget vote. However, faction whip Zahava Gal-On announced Saturday night that now the budget will safely pass, Yahad will revert to its initial position and vote against the budget.

Efforts will also continue Sunday to ensure the two-member United Arab List abstains. Sharon associates said that even though UAL's assistance is no longer needed, negotiations with them will continue so as "not to burn a bridge we had planned on crossing."

Aluf Benn and Moti Bassok contributed to this story.