JERUSALEM—Israeli Prime Minister Benjamin Netanyahu will easily win a snap election set for April 9, according to an opinion poll on Dec. 25, the first to be published since the ballot was announced. Netanyahu announced the early election on Dec. 24, appealing directly to voters for a fresh political mandate that could help him weather possible charges in corruption investigations. An election had not been due until November 2019. The survey, published in Israel’s Maariv newspaper, showed Netanyahu’s Likud party winning 30 of parliament’s 120 seats, the same number it took in the last election in 2015, and a governing...