Isaac Herzog (centre L) and Tzipi Livni (centre R), co-leaders of the center-left Zionist Union party, campaign outside a polling station in Modiin near Tel Aviv March 17, 2015. Prime Minister Benjamin Netanyahu faced a fight for his political survival on Tuesday as Israelis voted in an election that opinion polls predict the centre-left opposition could win. If he narrowly loses the vote, Netanyahu is probably still better placed than the opposition Zionist Union to cobble together a coalition, setting him on track to become Israel's longest-serving prime minister. REUTERS/Ronen Zvulun (ISRAEL - Tags: POLITICS ELECTIONS)