(CNN) -- Former Israeli foreign minister and opposition leader Tzipi Livni submitted her resignation from the Knesset Tuesday.
Speaking to reporters outside the parliament, Livni said, "My principles and values obligate (me) to leave the party of Kadima in the Knesset. I always said the seat was not everything. I am leaving at this stage but I am not retiring from public life"
Livni, who served as the head of the centrists Kadima Party, was defeated in a party leadership preliminary last month, losing to her party deputy and former Israel Defense Forces chief Shaul Mofaz, who took 62% of the votes to Livni's 38%.
The resignation adds another variable in Israel's quickly evolving political landscape. Earlier this week Prime Minister Benjamin Netanyahu indicated that he was likely to seek early elections. Some of his Likud Party officials predicted that the vote might be scheduled as early as September.
Livni was a vocal and high-profile but largely ineffective opposition figure to Netanyahu's rightist coalition.
In her remarks, Livni took Netanyahu's government to task for not putting enough effort into making peace with the Palestinians. "For many years our leadership has been burying its head in the sand dealing with political tricks" she charged.
"During this time the threats to Israel have only become greater ... In order to know this we don't the need evaluation of the head of the Shin Bet," she said in an indirect reference to recent criticism the former head of Israel's internal security lodged toward the current government's foreign policy.
Livni also lambasted the Netanyahu government for not doing more to enhance Israel's global standing.
"Israel lives on the top of a volcano and the international clock is ticking," she warned, saying the existence of democracy in the Jewish state is under "a great threat"
Livni, 53, gained international prominence in 2009 as foreign minister under Prime Minister Ehud Olmert.
She and Defense Minister Ehud Barak spearheaded Operation Cast Lead, Israel's extensive military offense in Gaza. She also played a major role in helping end Israel's 2006 war with Hezbollah in Lebanon.