FACTBOX: Key facts about Israel's Tzipi Livni

(Reuters) - Opinion polls show Israeli Foreign Minister Tzipi Livni is a favorite to win a Kadima leadership contest in September to replace Ehud Olmert, who said on Wednesday he would resign as prime minister when a new leader is chosen.

Here are some facts on Livni:

* Livni, 50, has already launched a campaign to replace Olmert. She called in 2007 for Olmert to step down following the release of an official report sharply criticizing his handling of the 2006 war in Lebanon.

* Livni was born in Tel Aviv on July 8, 1958, and is a leading member of the Kadima Party. She is Israel's second woman foreign minister, the first was Golda Meir who later served as prime minister from 1969 to 1974.

* Livni was elected to the Knesset as a member of the Likud party in 1999. She was one of Kadima's founding members alongside former Prime Minister Ariel Sharon, who split from Likud in 2005.

* She has been a rising star since taking her place in Sharon's inner circle. A former operative with Israel's foreign intelligence agency Mossad, she served as justice minister under Sharon.

* Livni comes from a well-known ultranationalist family but has endorsed withdrawal from some occupied lands as a pragmatic way to preserve Israel's Jewish majority -- if not to achieve a peace agreement. At times outspoken, she once called Palestinian President Mahmoud Abbas "irrelevant".