Prime Minister Ehud Barak's largest coalition partner threatened to quit the government today in a dispute over funding for its religious school system. The withdrawal of the powerful, ultra-Orthodox Shas party would leave Barak with a minority government that would likely be too weak to push through his plans for peace with Syria and the Palestinians.

Barak immediately asked for, and won, a 24-hour reprieve from the party to seek a solution to the budgetary impasse.

The threat by Shas, the biggest party in Israel's government after Barak's own Labor/One Israel bloc, seemed an act of political brinkmanship. If Shas leaves the government, it would likely lose funding for its 20,000-student religious schools, which are $24 million in debt. The schools' closure would undermine the party's political base.

Nonetheless, the threat created a crisis here and underscored the fragility of Barak's broad-based government, which spans the ideological spectrum from hawkish Russian immigrants and Zionist Jewish settlers to leftist peaceniks.

None of Barak's partners is more important than Shas, a theocratic party led by rabbis and backed by working-class Jews of Middle Eastern and North African descent. Shas holds a quarter of his coalition's 68 seats in the 120-member Knesset, Israel's parliament. The party controls four ministries in government and has broad influence over social welfare and health policy.

If Shas resigns from the government and shifts its 17 Knesset seats to the opposition, it would probably torpedo Barak's chances of gaining parliamentary support for any peace deal he might sign with Israel's Arab neighbors.

"This is a tactical move [by Shas], otherwise it is suicidal for both sides," said Hanan Kristal, a political analyst. "Each one would actually lose on his home court."

The crisis over Shas is timed to coincide with this week's deadline for passing Israel's 2000 budget. The party has demanded for weeks that the government step in to rescue its insolvent religious school network, which is independent of the public schools.

Yossi Sarid, the left-of-center and decidedly secular education minister, has insisted that before the government bail out the Shas schools, the party must devise a long-term financial plan for making the network solvent.