Some 116,000 registered members of the ruling right-wing Likud party in Israel started a polling process to elect a leader for the first time in 14 years, during which Benjamin Netanyahu was alone in the post.
Expectations favor Netanyahu's victory at the expense of his rival, Gideon Sa'ar, who was attacked by fierce supporters of Netanyahu and accused of treason.
The election results are scheduled to be released tomorrow, with the winner being nominated to head the Israeli government in the upcoming parliamentary elections early next March.
Charge list
However, this challenge increases the pressure faced by Netanyahu this year, who served as prime minister for four states and is fighting for his political survival after the prosecution charged him with a list of allegations of corruption.
Last November, prosecutors accused him of corruption in three criminal cases, and Netanyahu twice failed to form a government after two inconclusive rounds of general elections in April and September.
Benny Gantz, Netanyahu's opponent in those elections, also failed to form a coalition government, which plunged Israel into a political deadlock and led to a third election for the first time.
Although the problems facing Netanyahu, who is known among his supporters as "King Bibi", did not undermine their loyalty to him, some Likud members said that the time had come for a new leadership.