Benjamin Netanyahu won the race to become Israel’s prime minister not just because of his focused fight for the post. It was arguably because his main rival, Labor Party leader Isaac Herzog, failed to articulate an alternative political vision that would serve as an anchor for a realignment of Israeli politics. Israel’s dwindling left will continue to lose as long as it fails to understand that it must build deep, substantive alliances with some of Israel’s main religious, ethnic, and national constituencies.

Israel’s electoral system rewards the party head with the best chance of establishing a coalition, not the leader of the biggest party. So even had the electoral list that Herzog leads, the Zionist Union, secured several more Knesset seats than Netanyahu’s Likud, his lack of allies means he would still have most probably found himself back in opposition.

Furthermore, Herzog’s electoral strategy of drawing votes from the ‘soft right’ misread the Israel of 2015. Correctly identifying a weakness of Netanyahu, he strongly focused on socio-economic issues, including the high cost of living and growing income inequality. But he did not simultaneously provide convincing answers to Israel’s security challenges. While the right trumpeted assertive self-reliance, the Zionist Union, instead of presenting an innovative combination of security and diplomatic policies, belatedly offered a hollow, meager “diplomatic plan”. Many Israelis who enthusiastically support Herzog’s socio-economic agenda didn’t vote for his list because they doubted his credibility on security.

Worse, Herzog’s exclusive focus on Israeliness and Zionism looked incomplete. In today’s Israel, Jewish identity is no less vital. Again, even those centrist Israeli voters supporting his socio-economic agenda did not trust the Zionist Union when it came to educating their children and ensuring Jewish continuity in Israel.

To counteract this, Herzog should have forged substantive alliances with the real kingmakers in Israeli politics. These include the ultra-orthodox, Arab Israelis, disadvantaged Jews of eastern origin known as Mizrahim, and immigrants from the former Soviet Union.

Herzog has excellent relationships with members of all these groups in the Knesset, but personal ties alone cannot reconcile the divergent positions of the ultra-orthodox (Shas and United Torah Judaism) and liberal parties (Yesh Atid and Meretz), both of which the Zionist Union would have needed to win over in order to form a coalition. To bring both in, he needed to work with the ultra-orthodox leadership on a new social contract for Jewish identity in Israel: granting them more autonomy in exchange for loosening mandatory observance of Jewish Law; supporting economic rather than criminal sanctions to deal with draft-dodging by the ultra-orthodox; and promising to do more for a robust Jewish identity and education in the event of Israeli-Palestinian peace. Knowing peace would mean, for instance, more Torah study could have tempered the hostility of traditional, religious groups to his diplomatic agenda.

If Herzog wanted Arab Israelis to support him as prime minister, he had to address their concerns. To accommodate the growing Arab population, he could have promised to build as many as five or ten new Arab cities (defined in Israel as localities more than 50 percent Arab); since Israel was established, the state has established only one, and it is unpopular among Arabs. Herzog could have offered a bi-lingual university, in Hebrew and Arabic, so Israel’s Arab citizens could study in their own language. And Herzog could have reaffirmed their status as full citizens, for instance by issuing bank notes commemorating a prominent member of Israel’s Arab-Palestinian community, such as the writer Emile Habibi.

Jews of eastern descent form a majority in the country’s disadvantaged peripheral areas. Mizrahim representatives might have been tempted to support Herzog if based on a commitment to correct the discrimination of the periphery he had promised to redraw tax collection boundaries so that their home municipalities could capture additional taxes. Many Mizrahim work outside their home municipal boundaries, so taxes paid by their employers often don’t benefit them. He also could have addressed persistent fears that a peace agreement will trigger an influx of cheap Palestinian labor and increase unemployment in peripheral Jewish areas.

Many immigrants from the former Soviet Union, meanwhile, seek to preserve their heritage through expensive evening classes in Russian for children. Herzog could have offered to help with this.

Most fundamentally, Herzog should have understood that most Israeli voters no longer think of their country as a melting pot. Israeli society is diverse and wants to stay that way. Voters rejected what appeared to many as his vision of an Israel in Labor’s own image. Herzog should have demonstrated respect for other identity groups and suggested answers to their needs.

Such a political realignment, of course, would have come at a price. Some Zionist Union voters might have shifted to the liberal Meretz or Yesh Atid if they had seen Hertzog developing a strong relationship with the ultra-orthodox; other voters might have moved to the center-right if he secured Arab support.

Hertzog is a talented, thoughtful and savvy politician. He has already rejuvenated the Labor Party and positioned himself as a serious eventual contender to become prime minister. Now in opposition, he needs to rebuild the Left by weaving the diverse concerns of Israeli society into a compelling political vision. And if the pillars of Israeli politics endorse him for prime minister, the loss of some liberal votes, or even a few seats, will likely be inconsequential.

Such foundations would also augment the staying power of any future Labour coalition when it comes to any major movement towards the resolution of the Israeli-Palestinian conflict.

Ofer Zalzberg is Senior Analyst of Crisis Group’s Arab-Israeli Project.