Benjamin Netanyahu has informed Israel’s president he has been unable to form a coalition government after talks with his political rival and former army chief Benny Gantz broke down.

In a video statement published on Monday evening – the day of his 70th birthday – Netanyahu said he and his Likud party had worked “incessantly” to forge a “broad national unity government” with Gantz’s Blue and White party, but ultimately failed.

Netanyahu, Israel’s longest-serving leader, made the announcement just two days before the deadline to return the mandate to the president, Reuven Rivlin, who in turn intends to task Gantz, the head of the opposition, with the job of putting together a new government.

It would be the first time in over a decade that anyone but Netanyahu would be given the chance to head the Israeli government. But the move does not necessarily end Netanyahu’s political career, nor his chances of leading the country’s next administration.

Once he is formally asked by the president, Gantz will have 28 days to attempt to forge a coalition, or risk another election being called.

“The time of spin is over, and it is now time for action,” Gantz’s party said in response to the news, adding that it was “determined to form the liberal unity government, led by Benny Gantz, that the people of Israel voted for a month ago”.

Gantz’s chances do not look good and many in Israel predict he will also fail. Netanyahu was awarded the first shot at forming a government as he had marginally more support from lawmakers than Gantz. Neither leader, however, has a clear majority of 61 seats in the 120-seat Knesset and both have sought to stall each other’s dash for power.

Quick Guide The police investigations swirling around Netanyahu Show The Israeli PM is embroiled in four cases involving allegations of bribery and misconduct. He denies wrongdoing in every instance. Case 1000 is an investigation into gifts received on a regular basis by Netanyahu and his family from two wealthy businessmen, including cigars and pink champagne. Case 2000 is examining whether Netanyahu behaved improperly during a taped conversation with a newspaper publisher in which he appeared to try to negotiate more sympathetic coverage in return for lowering the circulation of a rival paper. Case 3000 is an inquiry into alleged kickbacks in a deal to buy German submarines. Netanyahu is not a suspect, but he was closely involved in the deal and the case has ensnared members of his inner circle.

Case 4000, the most serious, involves allegations that Netanyahu offered incentives to the Israeli telecoms company Bezeq in exchange for positive stories in an online news website it owns, Walla.

It is possible that if Gantz also fails, another parliamentarian could take the mandate, although they would need support from a majority of lawmakers, a position that currently appears extremely unlikely. If Israelis go to the polls again it would be the third time in a year, after two inconclusive election results pushed the country into a political crisis.

In May Netanyahu failed to cobble together a coalition following April’s muddied election result. Rather than giving the opposition a chance to forge a government, he instead pushed to dissolve the Knesset, triggering repeat elections and giving himself another chance.

Rivlin has been pressuring the two main parties to put aside their differences and form a unity government as together they would have more than enough seats for a majority.

In his statement Netanyahu said he had “made every effort to bring Benny Gantz to the negotiating table. Every effort to establish a broad national unity government, every effort to prevent another election.

“To my regret, time after time he declined. He simply refused.”

Gantz ran his election campaign on the promise to topple Netanyahu, making it difficult for the opposition leader to accept a power-sharing deal without losing credibility. Meanwhile, the prime minister has insisted his traditional allies from hardline nationalists to religious parties be included in any unity government, a precondition Gantz has rejected.

The next few weeks are not only crucial for Netanyahu’s political life, but also possibly his freedom. Israel’s attorney general is currently deciding whether to indict him in three potential corruption cases.

If he retains the role of prime minister, he will not be required to step down, even if indicted. Netanyahu has denied all allegations.