FACTBOX: Israel leadership vote and what follows

(Reuters) - Israel's ruling Kadima party elected Tzipi Livni on Wednesday to succeed Prime Minister Ehud Olmert, exit polls showed.

Olmert has said he will step down because of corruption investigations.

The following are mechanics of how Livni may, or may not, become prime minister.

-- Even after Olmert tenders his resignation to Israeli President Shimon Peres, he remains caretaker premier until Livni, or someone else, forms a new government -- a process that could take weeks or months.

-- To form a government, Livni will need a formal mandate to do so from Peres. The head of state can take up to 14 days to grant it after hearing recommendations from all the factions in the 120-seat parliament.

-- Once nominated, Livni, or whoever else Peres nominates, will have 42 days to conclude a coalition agreement with other parties. Failure could technically lead to Peres mandating someone else to go through the same process but further failure would trigger an election.

* Olmert could avoid spending time as caretaker prime minister by announcing he will take a leave of absence. In such a case, Livni, who is his first deputy, would take over as acting prime minister for up to 100 days and could then ease into the job at the head of the current coalition.

* Kadima has 29 seats in Israel's Knesset, the parliament, and depends on the 19 seats of the Labour party, led by Defence Minister Ehud Barak, for the core of a coalition. If Barak or others refuse to follow Livni, then parliament, which reconvenes on October 26, could vote to dissolve itself. An election would then have to be held within five months. More probably it would be in early 2009, although the next election is scheduled to take place in 2010.