Following Lieberman's recommendation of Netanyahu, Foreign Minister Tzipi Livni said she plans to take the centrist Kadima party into the opposition rather than accept offers to join Netanyahu in a unity government.
Ayalon's most difficult task may be explaining domestic proposals that have earned Lieberman comparisons to far-right French politician Jean-Marie Le Pen.
The Moldovan-born immigrant says that Israel's Arab minorities – one-fifth of the population – threaten to destabilize the Jewish state, just as ethno-religious conflicts sowed turmoil in the Balkans. The problem is even more acute in Israel, because it sits at the "clash of civilizations" divide between the West and radical Islam.
The "Israel is Our Home" party advocates passing a law requiring Israeli citizens – including some 1.4 million Arabs – to swear loyalty to the country's Jewish symbols or lose voting rights. As part of a solution to the Israeli-Palestinian conflict, Israel should redraw its border with the West Bank to cede hundreds of thousands of Israeli Arabs to a Palestinian entity in return for sovereignty over Jewish settlements.
Ayalon insists that Lieberman is a pragmatist who has been unfairly attacked campaign of "name calling." Once a part of the government, the hardball rhetoric of the opposition will ease, he predicts.
Some says it's too late. After his party's recent campaign slogan of "no loyalty, no citizenship," Lieberman would be disastrous choice, says Yossi Klein Halevi, a fellow at the Shalem Center's Adelson Institute for Strategic Studies in Jerusalem.