Benny Gantz has not yet officially announced he is entering politics.

If and when he does, it is not even clear whether he will be founding a new party or joining an existing one.

Nevertheless, the former IDF Chief of Staff’s as-yet non-existent and unnamed party is soaring in the polls.

In the most recent, it established itself as the second largest in the next Knesset, winning a notional 13 per cent of the vote, or 16 Knesset seats, overtaking the Zionist Union, which includes Labour, and Yesh Atid.

More intriguing and potentially groundbreaking is that, unlike those two existing parties, the polls indicate that a new party led by Mr Gantz could take away votes from the right-wing-religious bloc of parties, creating a possible stalemate.

The tight circle of advisors around former Lieutenant General Gantz are fully aware of the dangers of peaking too early in the race, which is one of the main reasons he has yet to announce. But the strong polling means that he is now unlikely to join one of the other parties that have been wooing him for the past year and instead establish his own political base, perhaps joining up with another party at a later stage.

Mr Gantz has two things working for him. He is a former Chief of Staff, and as such has the kind of security credibility that few Israeli politicians can rival and, so far, he is unsullied by any scandal.

His political views are known to be slightly left-of-centre but since he has barely ever spoken about them in public, he could then run a right-of-centre campaign, appealing to a wide range of floating voters.

Should Benjamin Netanyahu be worried? For now at least, his Likud is still firmly in the lead and by a wide margin.

His two main electoral assets remain in place: he still leads strongly in any survey asking Israelis who they see as the most suitable candidate for prime minister, and his rivals are hopelessly fragmented.

Alongside Mr Gantz’s potential new party is another, led by MK Orly Levy-Abekassis, which would take the number of centrist parties — if you include Kulanu, led by Finance Minister Moshe Kahlon — to five. More could be on the way.

A fifth election victory for Mr Netanyahu in 2019 still seems the likeliest outcome, unless enough of the massive egos leading the centrist parties can somehow unite in one list. Right now that seems a remote possibility.

But the prime minister’s troubles will begin after the election. Building a stable coalition out of so many rival parties, especially if his right-wing, religious base is eroded and lacks an outright majority, will be a nightmare.

And even after such a coalition is formed, it may not contain enough members willing to continue standing by Prime Minister Netanyahu if the attorney general decides to indict him on corruption charges.

That is why Mr Gantz and other party leaders are loath to unite under a joint banner. They all know their chances of beating Mr Netanyahu in the upcoming election are vanishingly slim but all are preparing themselves for the succession battle on the day he is forced to leave.