Israeli Prime Minister Benjamin Netanyahu called on his main challenger Benny Gantz on Thursday to form a unity government, a major development after deadlocked election results put his long tenure in office at risk.Netanyahu, in a video message, said he preferred to form a right-wing coalition, but the results showed it was not possible.READ | Israel elections: Netanyahu's rule threatened by deadlocked Israeli pollsThe stark admission followed Israel's general election on Tuesday that has threatened Netanyahu's status as the country's longest-serving prime minister as he faces possible corruption charges in the weeks ahead."During the elections, I called for the establishment of a right-wing government," Netanyahu said in a video message."But unfortunately the election results show that this is not possible."He went on to call on Gantz to form a "broad unity government today."READ | Israel votes on Netanyahu's political survivalNo response yetGantz had not yet responded publicly, but he has repeatedly called for a unity government.Following Netanyahu's message, at a memorial for the anniversary of the death of ex-president Shimon Peres that both attended, the two men shook hands.It is unclear, however, if Gantz, who has in the past spoken of not wanting to serve in a government with an indicted prime minister, would accept such a government with Netanyahu remaining as premier.The ex-military chief, who has mounted his challenge to Netanyahu without any prior political experience, was due to speak to journalists at 13:30 (10:30 GMT).Netanyahu was seeking to seize momentum by announcing his intention to form a unity government and head off attempts to oust him.Blue and White, a centrist alliance, has in the past sought to appeal to members of Netanyahu's right-wing Likud to abandon him and form a unity government with it.But there has so far been no signal that any Likud members would be willing to do that, and in his speech following the closure of Tuesday's polls Gantz made no such demand.Official results have not been announced, but Israeli media have reported that Blue and White has 33 parliamentary seats and Likud 31 out of 120 with 97% of the votes counted.