Will Israel be able to form a unity government?

Why has a possible national unity government with rotating Prime Ministers even been discussed by commentators during the present crisis?

Because after the 1984 elections Shimon Peres, who as President will have to decide next week whom to invite to form a coalition, found himself as a party leader in a situation - in one respect - similar to Tzipi Livni's now.

The Labour Alignment, which he headed, was the biggest single party - with 44 seats - but proved unable to form a workable coalition. After lengthy negotiations with Yitzhak Shamir, who as leader of Likud had secured 41 seats, Mr Peres reached an agreement for the two men to alternate. Mr Peres would serve as Prime Minister for two years, with Mr Shamir as foreign minister and deputy Prime Minister. After that the two men would swap places.

The deal was honoured - and the government functioned. The military withdrew to an Israeli-controlled security zone in southern Lebanon, for example, and runaway inflation was curbed. However with Mr Shamir in office as premier after 1986, Foreign Minister Peres negotiated in secret talks with Jordan's King Hussein the mechanism of an Israel-Jordan treaty and a wider UN Security council push for negotiations to end the occupation. Shamir was against the deal and the Cabinet tied when it discussed it, ensuring its demise. In December 1987, the first intifada erupted.

There was however one important difference between then and now. In 1984, neither major party was in a position to form a stable majority of more than 60 seats in the 120 seat Knesset without bringing in the other.

Labour would have to depend on the communists, and Likud on two ultra-orthodox and explicitly anti-Zionist parties. This time Mr Netanyahu is able to form a narrow coalition of the right - even though he might well ideally prefer to do otherwise, not least to maintain workable relations with the US.