Triumphant after quashing a mini-revolt within his party, Benjamin Netanyahu faces what is likely to be a gruelling campaign to win Israel’s third national election in a year with damning corruption indictments still hanging over him.

Israel’s longest-serving prime minister, famed for his political acumen in escaping seemingly impossible situations, won a primary leadership contest held on Thursday by a landslide.

His challenger, a former protege turned rival, 53-year-old Gideon Sa’ar, took just 28% of the vote from members of the ruling rightwing Likud party. Netanyahu, 70, defeated him with 72%, or 41,792 votes.

Having dominated Israeli politics for much of the past three decades, Netanyahu claimed a “giant victory” but he faces a much bigger battle in March when about 9 million Israelis will decide if he is worthy of re-election.

A third national vote within a year is unprecedented in Israel. Two previous elections provided inconclusive results – neither the Likud nor the opposition, headed by the Blue and White party, came out with a clear lead, and neither Netanyahu nor the former army chief of staff Benny Gantz, who heads Blue and White, were able to form a coalition government.

Israel’s president, Reuven Rivlin, had attempted to avoid another costly election cycle by pushing Likud and Blue and White to agree to a power-sharing deal, but that effort failed. With only a caretaker government in power, budgets cannot be approved.

The past two elections have proved deeply divisive, with Netanyahu in particular accused of exploiting anti-Arab sentiment to invigorate his base.

“We’ve been sentenced to another few blood-, sweat- and tear-soaked elections, filled with incitement, baseless hatred and curses,” the prominent columnist Ben Caspit wrote in the national news outlet Maariv on Friday.

“Israel is a country that is not being managed. It is frightened, managing itself, putting out fires and dodging catastrophes, hoping for the best and totally subjugated to the needs of one family,” he said, in reference to the Netanyahus.

The next election could be the most important of the prime minister’s career. His best chance of avoiding prosecution in three cases that include the severe charges of bribery, fraud and breach of trust is to win. Only with a majority in the 120-seat parliament, the Knesset, can he be granted immunity.

Responding to the Likud primary result, Gantz said his opponents had become “the Netanyahu party”, electing a man “who is seeking to unravel the rule of law and secure personal immunity, rather than address the actual concerns of the Israeli people”.

The supreme court is assessing whether it believes an indicted Knesset member can even be elected prime minister. A unfavourable ruling before the election could prematurely end Netanyahu’s 10-year streak in high office.

It is unclear how the indictments will affect the vote. Netanyahu has denied all charges, publicly lambasting the media, police and prosecutors for leading a “witch-hunt” against him.

Early polling suggests March’s vote will produce a similar result, which would extend the political crisis well over a year and plunge Israel into further uncertainty.