There's only one offer that Kadima head Tzipi Livni should accept from presumptive Prime Minister Binyamin "Bibi" Netanyahu in their ongoing coalition talks: rotation of the prime ministry in a true national-unity government of Kadima and Likud, with junior partners to round out the majority needed.
In theory, the Likud and Kadima together only have 55 mandates and not enough to form a government. However, Ehud Barak's Labor Party, with 13 mandates, gives them a comfy 68-vote majority that they can then bring to other parties on the contingency that they play ball or sit in opposition. Yes, Barak has said that Labor prefers to sit in opposition, but the right offer and the right parties excluded from the coalition could persuade Labor to join Likud and Kadima. However, a power-sharing agreement might very well be the linchpin in such a bloc being formed.
The leaks out of Israel are that Bibi is going to offer Kadima two of the three most important ministries: foreign affairs, defense, and finance. It's not clear whether Bibi has decided to keep one of these ministries for himself or another Likudnik or put all three on the table before Livni and say "pick any two." If it's the former scenario, the prospect of the Likud in the defense or foreign affairs ministry is downright frightful, and Livni should say no. If the latter, she should insist Bibi have finance and that she have foreign affairs and defense. (Defense could then either go to former Chief of Staff and Kadima No. 2 Shaul Mofaz or stay with current Defense Minister Barak, either in the government or as a non-government minister.)
But even if Kadima is given two ministries of its choice, why is it important that Livni demand the prime ministry in a rotation? Perhaps the better question is why Bibi feels that the prime ministry is rightfully his. Everybody, Bibi included, knows these election results come down to a simple choice for Netanyahu: He can be the prime minister over a far-right government that will accomplish nothing and last perhaps a year before people start getting cranky, or he can be prime minister for half of a full Knesset term over a centrist government.
The question ultimately is this: Would Bibi rather be the top man on the moon or share the top spot here on planet Earth? Livni should put the question to him just like that. Even Bibi, if he his the pragmatist we're told he is, should see the light. But his hubris is epic, as was learned in the 1990s. So I'm not hopeful.
Prediction: Bibi as Prime Minister and Likud holding the defense portfolio to an MK to be named. Silvan Shalom as foreign minister, unless a top ministry is demanded by Lieberman, in which case Bibi isn't stupid enough to give him anything but finance. Yisrael Beiteinu to get interior ministry and Shas to get religious affairs. Some arm-wrestling to determine who gets immigration portfolio.
We'll see how wrong I was tomorrow.