Former opposition leader Tzipi Livni announced her resignation Tuesday from the Israeli parliament weeks after losing the leadership of the centrist Kadima Party.
Livni said although she was leaving parliament, known as the Knesset, she intended to remain an active member of the Kadima Party.
The state of Israel is too dear to me to stop working for its interests, Livni told reporters before officially handing in her letter of resignation, the New York Times reported.
Livni was unseated by rival Shaul Mofaz as head of the Kadima Party during a primary election in March. Commenting on the defeat, Livni said she did not regret holding positions that might have factored into the loss.
She said she was not sorry for not backing down in the face of political blackmail -- even when the price was being in the government -- and for not willing to sell the country to the ultra-Orthodox, BBC News reported.
And I'm definitely not sorry for the main issue I promoted. Even if the Israeli-Palestinian conflict isn't in vogue right now, there's an urgent need to reach a permanent agreement with the Palestinians as well as with the Arab world, she added.
Livni's measured approach to reaching a peace agreement with Palestinians contrasted with Prime Minister Benjamin Netanyahu and his center-right Likud Party's more hawkish mentality, causing her to lose standing among Israel's more conservative-leaning constituencies.
Livni is credited with helping Kadima win a plurality of the 120 seats in the Knesset in the 2009 elections, though recent polls indicate that the party is likely to lose more than half of the 28 seats it currently holds.
Mofaz has asked Livni to help the party regain power in the upcoming elections, which Netanyahu may hold as early as this summer, though his term runs through late 2013.
Before resigning, Livni warned that Israel's existence was threatened by the policies of its current leadership under Netanyahu.
Israel lives on the mouth of a volcano, the international clock is ticking, and the existence of a Jewish, democratic state is at threat, Livni said, BBC News reported.
The real danger is a politics that buries its head in the sand, she added, saying that it did not take a Shin Bet chief to know that.
Livni was referencing a previous criticism of Netanyahu's policies on Iran made by the former head of Shin Bet, Israel's internal security agency, Yuval Diskin.