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. 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. 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. “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.” "We must not have a fourth election," he declared. Rivlin later addressed the new Knesset, with lawmakers having their temperatures taken before being brought into the chamber in twos and threes, to reduce risk of virus transmission. In remarks to a chamber empty but for Netanyahu and Gantz, he implored all lawmakers to end the impasse. "The citizens of Israel are exhausted," the president said. "I have just one request to make of you. Give (them) a government." Netanyahu -- Israels longest-serving premier and the first ever to be indicted in office, on graft charges -- has insisted that voters in the election gave him a mandate to continue as prime minister. Gantz made calls to Netanyahus religious allies on Monday, but was rebuffed for now. The head of the religious, nationalist Yemina party, Defense Minister Naftali Bennett, urged Gantz to let Netanyahu lead a short-term emergency government. The head of the ultra-Orthodox United Torah Judaism, Health Minister Yaakov Litzman, told Gantz he was focused on the fight against coronavirus and remained solidly behind Netanyahu. Rivlin has made clear he wants a government in place soon to help Israel beat back the pandemic. The president had summoned Gantz and Netanyahu on Sunday for an "urgent conversation", which ended without agreement, but Likud and Blue and White said the talks would continue.