As Israeli politicians enter the last rounds of negotiations over forming a new government, the most likely result is a right-wing, ultra-Orthodox coalition that a majority of Israelis, including the man forming it, doesn't want. And the government most Israelis do want--a national unity coalition of Likud, Kadima, and Labor that would deal with the threat of a nuclear Iran and its proxies along the Israeli border--is likely to be prevented by petty politics.

Though opponents of Likud leader Benjamin Netanyahu revile him as an opportunist, he has actually been acting in the national interest over the past few weeks, desperately wooing Kadima and offering it the cabinet’s top posts, including defense and foreign affairs. And though Kadima leader Tzipi Livni insists she represents a new style of altruistic politics, she has placed her own interests ahead of the nation’s.

Livni claims she has rejected Netanyahu’s overtures because he won’t commit to a two-state solution. But she knows that that disagreement is theoretical, because there is no chance anytime soon of creating a viable Palestinian state: As long as Hamas dominates Palestinian politics, it will impose a veto on any agreement. Nor has Livni managed to negotiate an agreement with Fatah. Livni, after all, served as foreign minister in the outgoing Kadima-Labor government of Ehud Olmert, which had three years to deliver peace with the Palestinians. In fact, Olmert tried to deliver two peace agreements--with the Syrians as well as the Palestinians. Instead, he became the first prime minister to fight two wars in one term--and not because he didn’t try to bring peace.

The real reason for Livni’s rejection of a unity government is that she is hoping a right-wing coalition will fail, opening the way for yet another round of elections. That is a realistic scenario: Netanyahu’s coalition is likely to be a constant battlefield over religious issues between the ultra-Orthodox Shas party and Avigdor Lieberman’s secular Yisrael Beitenu party. (Lieberman’s agenda won’t be imposing a loyalty test on Arab Israelis, as most Western observers have focused on, but rather promoting the secular interests of his Russian voters.)

In normal times, Livni’s calculations would be fair politics. But this is the most dangerous moment in Israel’s history. Sometime in the coming year, according to Israeli intelligence, Iran will cross the nuclear threshold. The next Israeli prime minister will have to make a decision unprecedented in its potential consequences: either to launch a preemptive strike against Iranian nuclear facilities and risk a multi-front war along Israel’s borders together with a missile assault on Tel Aviv, or else learn to live with a nuclear Iran imposing apocalyptic blackmail on the Middle East.

No Israeli leader has focused more consistently on the Iranian threat than Netanyahu. During the recent elections, he invoked the approaching nuclear deadline more than any other candidate. Netanyahu knows that, in order to effectively confront Iran, Israel needs a good working relationship with the Obama administration--an unlikely possibility with the emerging right-wing coalition.

A unity government would reflect a little-noted but historically significant outcome of the elections: the marginalization of the ideological left and right. Meretz, which won only three Knesset seats, is the only party that represents the old Peace Now agenda. And the National Union party, which won only four Knesset seats, is the only right-wing party that placed settlement expansion at the top of its agenda. In a narrow coalition, though, those four seats will become crucial for the government’s stability. Netanyahu’s real problem won’t be Lieberman--who is an opportunist, not an ideologue--but Yaakov Katz, head of the National Union, who wants to be deputy defense minister, in charge of the settlements portfolio. Katz will constantly confront Netanyahu with the choice of alienating Washington or unraveling his coalition.

Israel’s political tragedy is heightened by irony. In the inverted world of Israeli politics, Ehud Barak, head of the left-of-center Labor Party, is more inclined toward national unity than Livni, head of the centrist Kadima. Barak, who is more hard-line on the Palestinians than Livni and who better understands the urgency of the Iranian threat, would readily serve as defense minister in a unity government, but he has little support for that move from his party. By contrast, there is support in Kadima for a unity government. In a rational system, then, Barak and Livni would head each other’s parties.

Israel’s first unity government was formed just before the Six-Day War, only after Arab armies were amassing on the country’s borders and Israelis feared for their survival. That precedent will likely be the model for how the next unity government will be formed--at the very last moment before the Iranian crisis becomes unavoidable. But until that moment, with a right-wing coalition now the most likely option, Israel will endure increasing tensions in its relations with America and bitter domestic upheavals that lay just ahead.

Yossi Klein Halevi is a contributing editor to The New Republic, and a senior fellow in the Adelson Institute for Strategic Studies of the Shalem Center in Jerusalem.

By Yossi Klein Halevi