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.”

The surprise partnership between the prime minister and the former leader of the opposition had come a day after Mr. Netanyahu called for early elections because of cracks in his original coalition. The two men vowed to leverage the huge new majority to enact legislation ensuring that all citizens share the burden of military and civilian service, in the wake of a Supreme Court ruling invalidating a law that granted draft exemptions to thousands of yeshiva students.

The issue had broad resonance in a society increasingly torn between secular and religious Jews: some 20,000 people took to the Tel Aviv street this month to demand a broader draft and the ouster of politicians who opposed it.

But talks broke down over the details. Kadima set a goal of enlisting 80 percent of the ultra-Orthodox within four years, with stiff financial penalties for dodgers. Under pressure from religious parties long aligned with his Likud faction, Mr. Netanyahu proffered a more incremental solution, which Mr. Mofaz rejected as a cop-out.

“I was prepared to make compromises but I also had my red lines which I would not cross,” Mr. Mofaz told reporters Tuesday night after Kadima’s Parliament members voted 25-3 to defect from the coalition. “No more lip service; it is time for actions.

“I look all those who serve and their families in the eye, and tell them with great honesty and integrity that we had fought for you,” he added. “It was not easy to join the government, and I had paid a public price for doing so, but leaving is the only choice.”

Mr. Netanyahu, for his part, released a statement regretting Mr. Mofaz’s “decision to give up on an opportunity to make a historic change.”

“The only way to implement this on the ground is gradually and without tearing Israeli society apart,” he said, “especially at a time when the State of Israel is facing many significant challenges.”

With Parliament scheduled to disband for a three-month recess next week, the lack of agreement on a new draft law leaves the issue in the hands of the Israeli Defense Force. An aide to the defense minister said Tuesday that recruitment of yeshiva students would begin in August, but hinted that it would move slowly.

The political question now is whether Mr. Netanyahu can keep control over the factions in the remaining 66-member coalition. The religious parties may be less eager to go to the polls now, with the draft question in the forefront after weeks of wrenching public debate. The wild-card remains Avigdor Lieberman, head of the conservative Yisrael Beiteinu Party, who has his own draft legislation scheduled for a Parliament vote Thursday.

“Now we have to see if there is a domino effect,” said Abraham Diskin, a political scientist at Hebrew University in Jerusalem. “It’s really now in the hands of Lieberman. Until we know what kind of deal was worked out between Lieberman and Netanyahu, we don’t know anything.”

The prime minister’s office declined to comment on whether it would call elections before the expiration of the current term in October, 2013, but many analysts said they expect the polling to be set for January or February.

With the economy strong and domestic terrorism all but disappeared, few doubt Mr. Netanyahu’s re-election, even if the draft failure has hurt him; now, it seems clear he will run from the right, and less likely that he would take steps on settlements or the broader Palestinian conflict that might alienate conservative and religious voters.

Far less clear is what will become of Kadima, a center-left party that broke away from the Likud in 2005 and has lost traction in recent months.

Tzipi Livni had been replaced by Mr. Mofaz as Kadima’s leader shortly before it teamed up with Likud in May, and some believe she will now make a comeback. Others are urging Ehud Olmert, the former prime minister acquitted last week in two key corruption cases, to retake the reins. Many believe Kadima will disintegrate, with right-leaning members rejoining Likud and others forming a new center-left movement.

Haim Ramon, a former Kadima Parliament member who has promised to birth a new party, on Tuesday said Kadima “is now a party that has lost its right to exist.” because it had joined a conservative government only to fail to deliver on its promises.

Robert Ibayev, one of several current Kadima lawmakers who have been considering splitting from the party, told Israel radio that “what happened today is shameful,” and described Mr. Mofaz’s leadership as “a failure.”

Outside Kadima, politicians were quick to crow.

“Just as water and oil do not mix, it is about time that the relationship between the Likud and the spineless party that is called Kadima come to an end,” Danny Danon, the only Likud lawmaker who voted against the coalition deal, said in a statement. “Kadima is an empty shell with no ideological core and will soon disappear from the Israeli political landscape.”

Isaac Herzog, chairman of Parliament’s Labor Party faction, said the short-lived partnership would hurt both Likud and Kadima.

“We are very sorry that Mofaz and Kadima have dragged the Israeli people for months with a futile effort on all fronts,” he said. “Right now the only real option and the right thing to do is for Netanyahu to move to elections instantaneously without further delay.”