Benny Gantz has set himself the ambitious target of forming a new Israeli government on March 23. For now at least, he does not have the numbers to do so. But he is banking on a surprising collection of partners and supporters for the task.

While minority governments are rare in Israeli political history, they are simple to form. To swear in a new government, the potential prime minister needs only to win the confirmatory vote in the Knesset — by any majority.

Once in office, he or she can only be removed by a “constructive” no-confidence vote in favour of another prime minister who this time must have the support of at least 61 MKs, an absolute majority.

Since the coalition supporting Benjamin Netanyahu won 58 seats in last week’s election and can all be expected to oppose a Gantz government, the Blue & White leader needs at least 59 opposition MKs to back him.

That means Mr Gantz is now openly trying to unite the assorted communists, Arab nationalists and Islamists of the Joint List along with Yisrael Beitenu’s Jewish nationalists behind him.

It seems an impossible feat and, no less importantly, Mr Gantz and his Blue & White colleagues denied before the election that they would do it.

On Tuesday and Wednesday, Blue & White’s leadership met the other three opposition parties to coordinate their endorsements when President Reuven Rivlin begins to seek parties’ views on Sunday.

It was hardly coincidental that while the meetings with Yisrael Beitenu and Labour-Meretz featured Mr Gantz himself, with his top colleagues, the representatives who met the Joint List were senior but decidedly second-tier. Blue & White also did not release a statement or photos from its meeting with the Joint List.

But it was still a historic moment: Israel’s main centrist party had met representatives of all the four parties in the Joint List, including the Arab-nationalist Balad.

Blue & White is trying to downplay it.

The party’s number two, Yair Lapid, tried to reassure his followers on Facebook that “despite all the lies Bibi is spreading, the Joint List won’t be part of this government. They will vote once from outside and that’s it.”

But the bottom line is that the Israeli mainstream is reaching out to the non-Zionist Arab parties for support for the first time.

Even Yisrael Beitenu’s Avigdor Lieberman, who has been calling the Arab MKs “traitors” for many years, will not rule out the scenario. He kept the pressure on the prime minister on Wednesday by saying he did not have to give “advance information or tranquilisers to Netanyahu”.

The opposition is frantic to replace Benjamin Netanyahu and avoid a fourth election, and its only way of doing so is to join forces in an hitherto unimaginable alliance.

But now that even Mr Gantz’s hardline right-wing partner, Blue & White’s number three Moshe Yaalon, are prepared to break Israeli politics’ biggest taboo, can it even happen?

Balad and its three MKs are ideologically opposed to supporting any Zionist government. It is not clear if they can be cajoled by their Joint List colleagues to vote in favour this time, or at least to abstain.

But even if Balad were cooperative, it would not be enough if other opposition MKs did not support a Gantz minority government.

On Tuesday night, Gesher’s sole MK Orly Levy-Abekasis said she would not vote for a government supported by the Joint List. Two Blue & White MKs, Yoaz Handel and Zvi Hauser, are silent objectors.

And then there is the mysterious Mr Lieberman, who will announce his decision at the very last moment.

But even if Mr Gantz fails to form the minority government he desires, both he and the Joint List will have crossed a rubicon.

An Israeli government supported by the Arab parties is no longer unthinkable and this will have profound future implications for Israel’s politics and society.