JERUSALEM — Israel's embattled Prime Minister Benjamin Netanyahu faced off against longtime rival Gideon Saar for the Likud party leadership on Thursday, in a contest that could threaten his grip on power.

A defeat for Netanyahu, 70, would be a shock, but even a relatively close result could weaken his influence over the conservative party he has dominated for 20 years.

In power as premier for a decade, Netanyahu early next year faces a third general election within 12 months and has been indicted in a multi-pronged corruption probe.

But to lead Likud into the next national poll, he must overcome the internal party challenge.

Polls in that party race opened across the country at 09:00 a.m. (0700 GMT), with Likud's roughly 116,000 eligible voters having until 11:00 p.m. to choose between Netanyahu and Saar. Results are expected early Friday morning.

At a polling station in the Kiryat Moshe neighborhood of Jerusalem, Rami David said he voted for Saar because "he would give Likud a new image."

Saar, 53, has been a senior figure in the Likud for a decade and held multiple ministries.

He is seen as slightly to the right of Netanyahu and has called for an even more hawkish policy towards the Palestinians.

Nathan Moati, 26, backed Netanyahu and didn't think supporters were concerned by the indictment.

"The most important thing is to vote overwhelmingly — we need to have 80/20 (for Netanyahu)."

Saar and Netanyahu have spent recent days crisscrossing the country, with Saar seeking to portray himself as a more electable leader.

The campaign's most dramatic moment came on Wednesday evening when Netanyahu was rushed off stage while campaigning in Ashkelon in southern Israel near Gaza, after what the army called a "projectile" was fired from the Palestinian enclave.

Stephan Miller, a pollster who has worked on multiple Israeli campaigns, said whatever the result "Netanyahu can only lose."

No matter how much support Saar receives, "it will be the first time in 10 years that a group of voters on the right explicitly express their desire to get rid of Netanyahu," he said.

"If that is more than a third of the party, Netanyahu will be significantly damaged."

The winner of Thursday's vote will lead Likud into Israel's third national poll within 12 months.

The general elections in April and September saw Netanyahu deadlocked with centrist challenger Benny Gantz, neither of them able to command a majority in Israel's proportional parliament.

Last month, Netanyahu was indicted for fraud, bribery and breach of trust in three corruption cases, allegations he strongly denies.

The primaries were called shortly after, the first internal challenge to Netanyahu since 2014.

A series of polls in recent weeks have indicated a Saar-led Likud might win fewer seats in a third election than under Netanyahu, but the overall right-wing bloc might be larger — potentially yielding a viable governing coalition.

Saar has not attacked Netanyahu personally, even hinting he would support him becoming Israel's president.

A source close to Saar insisted his camp was hopeful of an upset.

"More and more, the Likud rank and file are understanding the choice is between Netanyahu and being in opposition versus Saar and being in government," the source said.

Netanyahu has sought to paint himself as an irreplaceable leader fighting a "witch hunt" by the police, the legal establishment and the media.

Other party figures seen as potential future leadership candidates — including parliamentary speaker Yuli Edelstein — have so far chosen not to support either candidate, despite pressure.

Ofer Zalzberg, an Israeli political analyst at the International Crisis Group think tank, said it would have been unthinkable a few years ago for senior party officials not to back Netanyahu publicly.

Major Likud players "already sense there is a changing of the guard. They are hoping that the contest between Saar and Netanyahu will create the conditions for a third party to take home the spoils," he said.

Netanyahu's downfall has been predicted multiple times since he became premier for a second time in 2009, but he has defied expectations and appears determined to fight on.

Under Israeli law, a prime minister is only forced to step down once convicted with all appeals exhausted. — AFP