After a long summer and Chagim break, members of the Knesset will be back in Jerusalem with only one issue on their agenda.

By law, elections must be held by November 2019, but the expectation is that the current coalition has passed its sell-by date and Israelis will be going to the polls in a matter of months.

The main reason for bringing the elections forward by eight or nine months is Prime Minister Benjamin Netanyahu’s calculation that he can strengthen his hand by winning a fifth term before the attorney general decides to indict him on multiple charges of corruption. Nearly everyone — including Mr Netanyahu himself — expects will this happen eventually.

The Prime Minister believes that a renewed mandate, which the polls predict voters will give him, will put him in a position to demand his coalition partners commit to staying in government even if he is indicted.

They may even agree a law, similar to the one in France, that grants leaders immunity from prosecution while in office. But that is for the horse-trading after polling day. In the meantime, there is a campaign to run.

Mr Netanyahu is resigned to the fact that, even if he succeeds in preempting the attorney-general, the election will largely be fought over his suitability for the job.

That could work in his favour, since many right-wingers suspect the investigations against him are all the result of a left-wing plot and could flock to Likud.

Centrist voters who have their doubts over the prime minister’s integrity will be bombarded with footage of his meetings with world leaders from Donald Trump to Vladimir Putin. The message will be that Israel has no other statesman and cannot afford to risk its future with inexperienced lightweights like Labour’s Avi Gabbay and Yesh Atid’s Yair Lapid.

The polls at least bear this out: the centrist parties are badly trailing Likud. Both leaders are fighting each other for second-place and Mr Lapid is widely expected to join the next Netanyahu government, where he hopes to fill the vacant post of foreign minister.

The prime minister’s main dilemma now is trying to calibrate his expected victory.

He has set his hopes on winning 35-40 Knesset seats, but to obtain a majority in the chamber of 61 seats and build what he hopes will be a more stable coalition, he will rely on other right-wing and religious parties, Likud’s traditional partners.

A successful election for Likud means that some of the parties that draw their voters from the same constituencies, especially Yisrael Beiteinu and Shas, could hover perilously close to the 3.25 per cent electoral threshold.

If they fail to enter the next Knesset, their votes will not count and the Likud bloc could lose seats, imperiling its majority and significantly weakening Mr Netanyahu’s hand in coalition negotiations.

He has already suggested lowering the threshold, but legislating changes to the electoral law so close to the elections will be difficult, even for him.

None of the coalition partners are happy. Two party leaders who fear losing voters to Likud — Yisrael Beiteinu leader and Defence Minister Avigdor Lieberman and Naftali Bennett, the Jewish Home leader who is Education Minister — were already in full election mode last week, trading accusations over the IDF’s handling of the situation on the Gaza borders.

The Chasidic and Lithuanian wings of Strictly Orthodox United Torah Judaism have already split ahead of this month’s local elections and may not be able to patch things up in time for the national election.

The centre-right Kulanu is also lagging in the polls, losing voters to Likud, Yesh Atid and other newly-forming centrist parties.

It is almost a foregone conclusion that Likud will be the largest party after the next election.

Mr Netanyahu’s battle will begin the following day, when he tries to rebuild his coalition and prepare for the indictments.