Tough competition

Even so, Netanyahu is the favorite in the leadership contest, campaigning on his accomplishments after years of leadership and the institutional loyalty of a party known for its dedication to its leader.

But ever the cautious politician, Netanyahu isn't taking anything for granted.

In an effort to energize his base, Netanyahu continued his us-versus-them tone, tweeting to his supporters: "They won't decide for us. Only we will decide who will lead the Likud and the country. A big victory for me in the primaries will secure a huge Likud victory in the Knesset elections."

His challenger is hardline right-wing politician Gideon Sa'ar, a former Minister of Education, who has promised to succeed where Netanyahu has failed, vowing to break Israel's political deadlock and lead Likud to victory in March.

"This is a fateful day for Likud and the country. Today we could bring change and new hope to the citizens of Israel, while ensuring the continuation of the right wing rule," Sa'ar tweeted on Wednesday morning.

Netanyahu has not faced a serious challenge to his leadership of the Likud in more than a decade.

He has garnered more than 70% of the vote in every leadership race since 2007. Such a victory in this race would ensure Netanyahu's control of the Likud and his leadership of Israel's right wing.

If this turns into a close race, it could signal that the Likud base is shifting away from Netanyahu and moving in a different direction, which could damage the PM in the upcoming national election in March.

Rockets during rally

In an effort to ensure support from the party's pro-settlement base, Netanyahu promised he would secure another major political gift from US President Donald Trump, who has already recognized Jerusalem as the capital of Israel, moved the embassy, and recognized Israeli sovereignty in the Golan Heights.

"We are going to bring American recognition of Israeli sovereignty in the Jordan Valley -- and pay attention -- in all of the settlements -- those in the blocs and those that are not," Netanyahu promised in a video message on Tuesday evening.

"That's the next step. It's in our hands. And only I will bring this."

The statement goes even further than Netanyahu's promise before the last elections in September, in which he vowed he would annex the Jordan Valley if he won the election.

When he failed to form a government for the second consecutive time, mirroring his failure after the April elections, Netanyahu was unable to act on his campaign promise.

CNN has reached out to the US State Department for comment. The White House referred CNN to the National Security Council, which declined to comment.

One day before the vote, while holding a campaign rally in Ashkelon Wednesday evening, Netanyahu had to be taken off stage as Gaza militants fired a rocket toward the southern Israeli city.

The rocket was intercepted by the Iron Dome aerial defense system.

A virtually identical situation occurred before the elections in September. Netanyahu was holding a campaign rally in the city of Ashdod, a few miles north of the city of Ashkelon.

Rockets were fired from Gaza into Israel, forcing security to escort Netanyahu off the stage. He returned a short time later to finish his speech.

Results of the leadership race are expected early Friday morning.