Isaac Herzog (R) and Tzipi Livni, co-leaders of Zionist Union, raise their arms at party headquarters in Tel Aviv March 18, 2015. Prime Minister Benjamin Netanyahu's main challenger, Zionist Union chief Herzog, disputed Netanyahu's victory claim in Israel's election on Tuesday, saying "everything is open". "This result allows us to return to power," Herzog told supporters at party headquarters in Tel Aviv after exit polls showed a tie between the centre-left Zionist Union and Netanyahu's right-wing Likud. REUTERS/Ronen Zvulun (ISRAEL - Tags: POLITICS ELECTIONS)