In this Oct 23, 2019 photo, Israeli President Reuven Rivlin (right) shakes hands with retired general Benny Gantz as he hands him a document as he tasks the latter with forming a new government, during a press conference at the presidential compound in Jerusalem. (GALI TIBBON / AFP)

JERUSALEM — Israeli opposition leader Benny Gantz received an official mandate on Monday to try to form Israel’s next government, and called on Prime Minister Benjamin Netanyahu to join him in a unity administration.

In a sharp blow to Netanyahu, who had declared victory in a March 2 election, 61 of parliament’s 120 legislators voiced support for Gantz, leader of the centrist Blue and White party, in consultations with Israeli President Reuven Rivlin on Sunday.

At a televised ceremony, Rivlin gave Gantz 28 days, with the option of a two-week extension, to assemble a ruling coalition.

I give you my word, I will do all in my ability to establish within a few days as broad and patriotic a government as possible 

Benny Gantz, Israeli opposition leader

But Gantz’s backers include opposing forces - the Joint List of Arab parties, and the far-right Yisrael Beiteinu faction led by former defense minister Avigdor Lieberman - that complicate efforts to form a viable government without wider support.

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Netanyahu and Lieberman have proposed a six-month “national emergency government” grouping Blue and White and the prime minister’s right-wing Likud party, to confront the coronavirus crisis.

“I give you my word, I will do all in my ability to establish within a few days as broad and patriotic a government as possible,” Gantz said at the nomination ceremony, without going into details.

Israel has held three inconclusive elections in less than a year, and Netanyahu faces a criminal indictment on corruption charges, which he denies.

Gantz, who in failed coalition negotiations with Netanyahu after a national ballot in September insisted on serving first as prime minister in a “rotating” leadership arrangement, called on his rival to agree to a unity deal now.

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“The time has come for an end to empty words,” Gantz said at the ceremony. “It’s time to set aside our swords and unite our tribes and defeat hatred.”