JERUSALEM — The broadest unity coalition Israel has seen in many years broke apart Tuesday evening, rent by irreconcilable differences over how to integrate ultra-Orthodox men and Arab citizens into the military and civilian service, a fundamental question for the future of the Jewish democracy.

After stunning the political establishment with a secret late-night deal in May, Prime Minister Benjamin Netanyahu and Shaul Mofaz, the leader of the centrist Kadima Party, failed to achieve their top priority and agreed to part ways. While Mr. Netanyahu retains power with his original, narrower majority in Parliament, analysts said the split weakened both leaders and was likely to hasten elections.

The coalition had given Mr. Netanyahu a supermajority of 94 of the Parliament’s 120 members and a new nickname, King of Israel, and with that unprecedented authority to take on complex issues like the stalemated peace process with the Palestinians and the national responsibilities of Israel’s growing minorities. Instead, when it came to the draft and expanding settlements in the West Bank, he chose to solidify his alliance with right-wing and religious factions.

“I don’t think there are any winners, except maybe the Orthodox parties — they’re off the hook for the foreseeable future,” said Yossi Verter, political correspondent for the newspaper Haaretz. “The losers are, of course, Netanyahu and Mofaz. When the leaders of the two big parties in Israel sit and decide to form a unity government and after 70 days it collapses, they don’t look like serious men. It’s like a joke.”