"We are all Keynsians now," Richard Nixon famously asserted just as the economic theories of John Maynard Keynes fell into disrepute. Likewise, one could have said with similar confidence in 1989, as Israel's existence reached wide acceptance, "We are all Zionists now." No longer.

Count the ways Israel is under siege: from Iranians building a nuclear bomb, Syrians stockpiling chemical weapons, Egyptians and Saudis developing serious conventional forces, Hizbullah attacking from Lebanon, Fatah from the West Bank, Hamas from Gaza, and Israel's Muslim citizens becoming politically restive and more violent.

World-wide, professors, editorialists, and foreign ministry bureaucrats challenge the continued existence of a Jewish state. Even friendly governments, notably the Bush administration, pursue diplomatic initiatives that undermine Israeli deterrence even as their arms sales erode its security.

Let's suppose, however, that the country muddles through these many problems. That leaves it face to face with its ultimate challenge: a Jewish population increasingly disenchanted with, even embarrassed by, the country's founding ideology, Zionism, the Jewish national movement.

As developed by Theodor Herzl (1860-1904) and other theoreticians, Zionism's call for a sovereign Jewish state fit the political context and mood of its time. If Chinese, Arabs, and Irish sought to establish a national state, why not Jews?

Indeed, especially Jews, for through nearly two millennia they had paid the greatest price of any people for their political weakness, having been expelled, victimized, persecuted and mass murdered as none other. Zionism offered an escape to this tragic history by standing tall and taking up the sword.

From its inception, Zionism had its share of Jewish opponents, ranging from the Haredim (Ultra-Orthodox) to nostalgic Iraqis to reform rabbis, But, until recently, these were marginal elements. Now, due to high birth rates, the once-tiny Haredi community constitutes 22 percent of Israel's current first-grade class; add to this the roughly equivalent number of Arab first-graders and a sea-change in Israeli politics can be expected about 2025.

Worse for Israel, Jewish nationalism has lost the near-automatic support it once had among secular Jews, many of whom find this nineteenth-century ideology out of date. Some accept arguments that a Jewish state represents racism or ethnic supremacism, others find universalist and multi-cultural alternatives compelling. Consider some signs of the changes underway:

*Young Israelis are avoiding the military in record numbers, with 26 percent of enlistment-age Jewish males and 43 percent of females not drafted in 2006. An alarmed Israel Defense Forces has requested legislation to deny state-provided benefits to Jewish Israelis who do not serve.

*Israel's Attorney General Menachem Mazuz has up-ended the work of the Jewish National Fund, one of the pioneer Zionist institutions (founded in 1901) by determining that its role of acquiring land specifically for Jews cannot continue in the future with state assistance. Continued...