JERUSALEM — Israeli Prime Minister Benjamin Netanyahu gave up on his month-long effort to negotiate a governing majority after September’s dead-heat national election, opening the way for his chief rival to try his hand at cobbling together a coalition to run the country.

If Israel's president gives former army chief of staff Benny Gantz permission to proceed, he would be the first politician other than Netanyahu given the mandate to form a government in more than a decade, although his own path to power is far from certain. Israel's complex - and gridlocked - political system all but ensures that the final outcome is not likely to be clear for weeks, and that a third election in less than a year may be required.

"This is new: This broadens the political imagination to include the possibility that someone not named Netanyahu could be the prime minister of the state of Israel," said Mordechai Kreminitzer, senior fellow at the Israel Democracy Institute. "But I think Gantz will also find it extremely difficult to shape a coalition."

Netanyahu's move came after power-sharing talks broke down almost immediately between his Likud party and Gantz's Blue and White party, the two biggest factions in the Knesset, Israel's parliament. The parties emerged from September elections with a nearly identical number of seats, and neither close to a controlling majority.

The prime minister released a video announcing an end to his efforts, two days before the deadline and on his 70th birthday, decrying Gantz's steady refusal to soften his resistance.

Netanyahu tapped by Israel's president to try forming a new government

Gantz's party has one more seat than Likud, but Netanyahu emerged with one more Knesset recommendation to form a government. Israeli President Reuven Rivlin awarded the prime minister the first official mandate, giving him 28 days to assemble a majority.

But despite pleas from Rivlin that the two sides find a way to form a unity government, neither party showed a willingness to budge on key demands, and Netanyahu told Rivlin he was giving up with just days left on his mandate.

Negotiators for the two parties met for several sessions without progress. Gantz spurned numerous invitations from Netanyahu for the two leaders to meet one-on-one, insisting through party statements that the prime minister is less interested in compromise than ensuring he serves first in any power-sharing rotation. Netanyahu is facing probable indictment on corruption charges and might see a unity government as an "immunity" government, as Gantz put it disparagingly.

"Regrettably, Likud is sticking to its precondition of Netanyahu first," Blue and White said in a statement after the negotiating session, before announcing it was bowing out of talks altogether. There have been no reported discussions in the two weeks since.

"Likud was shocked by the decision of Blue and White to blow up the negotiations," Likud said in a statement on the day Netanyahu's lawyers attended the first of four pre-indictment hearings on allegations of bribery and breach of trust.

Formal indictments on those charges are expected by mid-November, possibly.

Analysts say any real possibility of compromise won't arise until both sides have exhausted their efforts.

"For there to be concessions, there has to be ripeness," Kreminitzer said. "And in order to get ripeness, you have to fail some."

The concessions would be painful. Gantz has pledged throughout the campaign that he would only serve in a government with Likud if the legally besieged Netanyahu is not part of it. Netanyahu, for his part, has insisted that any Likud government must include the far-right and ultra-Orthodox parties in his coalition.

The two sides were hashing out a compromise suggested by Rivlin, under which they would share the prime minister's role on a rotating basis with Gantz effectively assuming power if and when Netanyahu becomes embroiled in the legal system. Netanyahu quickly agreed to the concept but couldn't bring along Gantz, who may think Netanyahu's position will only weaken as his legal case continues.

The prime minister's run at forming a coalition was tumultuous. As his attorneys spent four marathon sessions with the attorney general, he oversaw the start of the Knesset session and dealt with protests against spiking crime in Arab neighborhoods and the launch Turkish strikes against Kurds in Northern Syria. Netanyahu had built his campaign in part on his close friendship with the U.S. president, but that asset has been tainted by Trump's withdrawal of U.S. troops from northern Syria, widely seen here as a betrayal of a worthy Israeli ally.

At one point, perhaps to demonstrate his tight grip on the party, Netanyahu briefly proposed a snap leadership vote within his Likud party. But when one potential rival from within the ranks immediately expressed interest in running against him, he dropped the idea in favor of a vote of confidence at a sparsely attended meeting of the party's executive committee.

Netanyahu's return of the mandate may just be part of the complex gamesmanship that goes with coalition-building in a closely divided Israel. The first attempt to form a government may have been destined to fail, many analysts think, and theories abound that Gantz was secretly angling for his rival to get the honors.

Gantz would have 28 days to form a government, after which the president could then open the process for three weeks to anyone in the Knesset able to come forward with a majority of 61 seats. If that fails, the country could face its third national election of the year. That prospect probably will make the final 21-day push to form a government the most fruitful. Likud acknowledged as much, referring to the period as "the real show."

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The Washington Post’s Ruth Eglash contributed to this report.