JERUSALEM — Prime Minister Benjamin Netanyahu of Israel gave up on his latest attempt to form a government on Monday, clearing the way for Benny Gantz, the former army chief who narrowly defeated him in last month’s election, to try to become the country’s next leader.
Mr. Netanyahu, who turned 70 on Monday and has been prime minister since 2009, told President Reuven Rivlin that he had been unable to put together a 61-seat majority coalition in Parliament.
Mr. Rivlin said he would give Mr. Gantz, 60, leader of the centrist Blue and White party, the mandate to form a government “as soon as possible.” Under the law, Mr. Gantz will have 28 days to do so.
“The time of spin is over, and it is now time for action,” Mr. Gantz’s party said in a statement. “Blue and White is determined to form the liberal unity government, led by Benny Gantz, that the people of Israel voted for a month ago.”
It is unclear, however, whether Mr. Gantz will have any greater chance of succeeding. Mr. Netanyahu, who remains prime minister until a new government is formed, is counting on Mr. Gantz to fail. That could force a third election, a prospect that few Israelis aside from Mr. Netanyahu’s most devoted supporters would relish.
In a video posted to his Twitter account on Monday, shortly after the end of the Sukkot holiday in Israel, Mr. Netanyahu said he had “worked relentlessly, in the open but also in secret, in an effort to form a broad national unity government” with Mr. Gantz.
“This is what the people want,” Mr. Netanyahu wrote. “This is also what Israel needs in the face of security challenges that are growing by the day, by the hour.”
He said he had made “every effort” to negotiate a unity government with Mr. Gantz, but “to my regret, time and time again, he simply refused.”
Mr. Gantz, in his first run for office, tied with Mr. Netanyahu in their first contest in April. He narrowly edged Mr. Netanyahu’s Likud party on Sept. 17, but Mr. Netanyahu’s coalition of right-wing and ultrareligious parties came away with a larger bloc in Parliament than Mr. Gantz’s alliance of center-left parties, earning the incumbent the first attempt at forming a government.
The gamesmanship between Mr. Netanyahu and Mr. Gantz since the do-over election last month has resembled a chess match in which Mr. Netanyahu’s position was weaker but the conclusion was hardly foregone.
With neither man capable of achieving a 61-seat majority in Parliament that he finds politically palatable, a unity government of one sort or another appeared unavoidable, and Mr. Rivlin urged both men to agree on one.
One major stumbling block was the question of who would serve as prime minister first under any rotation agreement and at what point Mr. Netanyahu, who is facing a looming indictment in three corruption cases, would suspend himself if charged.
Mr. Gantz has long insisted that he would not serve under a prime minister facing indictment. Mr. Netanyahu accepted a proposal first suggested by Mr. Rivlin, the president, under which Mr. Netanyahu would serve as prime minister first, but if charged, would declare himself incapacitated for an indefinite period of time while he sorted out his legal troubles; Mr. Gantz would then serve as acting prime minister with full powers. Israel, in other words, would have had two prime ministers at once.
But such an arrangement left many open questions, including at what point Mr. Netanyahu would suspend himself, and would have required changes to Israel’s laws of governance, which could in turn be challenged in the Supreme Court.
Moreover, Mr. Netanyahu has insisted that any unity government include his longstanding allies in the right-wing and religious parties. Mr. Gantz has demanded that Likud, without its allied parties, negotiate a unity government with Blue and White.
Mr. Netanyahu repeatedly and publicly chastised Mr. Gantz for refusing to negotiate with him on terms for building a grand coalition including both their parties. Mr. Gantz said the terms proposed by Mr. Netanyahu were impossible to accept.
Most recently, Mr. Netanyahu asserted that Mr. Gantz’s plan all along was to thwart all efforts to form a unity government and instead set up a minority government with the parliamentary backing of the Arab parties — an unlikely move that would be deeply unpopular with many Blue and White voters, as well as with many of the party’s lawmakers.
The rise of such a minority government would only be possible with the tacit cooperation of Avigdor Liberman and his ultra-nationalist Yisrael Beiteinu party, which Mr. Liberman has all but ruled out.
Critics said Mr. Netanyahu had been showing signs of panic. He pressed his right-wing and religious allies to sign multiple loyalty oaths. And he proposed a Likud party primary, but then immediately canceled the idea after a popular younger rival, Gideon Saar, immediately declared himself ready to challenge Mr. Netanyahu for the party leadership.