JERUSALEM — Calling herself ‘‘an answer to the contention that there is no one to vote for,’’ Tzipi Livni, Israel’s centrist former foreign minister, returned to politics Tuesday after a six-month hiatus, heading a new party that she described as ‘‘an alternative, personal and ideological,’’ to Prime Minister Benjamin Netanyahu.
‘‘I’ve come to fight for Israel,’’ Livni, 54, said in an impassioned 20-minute speech at the journalists’ union office in Tel Aviv. ‘‘I haven’t come to fight against but to fight for.’’
She said she would ‘‘fight for peace, a peace of the sober,’’ “for the Jewish Israel,’’ and ‘‘for the democratic Israel, a state in which all, but all of its citizens, with no difference of nationality and religion, are citizens with equal rights.’’
Livni’s return, under the banner of ‘‘The Movement Led by Tzipi Livni,’’ immediately shook up the center of Israel’s political spectrum, with eight members of Parliament from the Kadima Party she helped found in 2005 bolting to join her, heralding its likely demise.
But in Israel’s coalition system of government, individual parties are less important than ideological blocs, and most recent polls have suggested that Livni and other existing opposition candidates will have a hard time taking enough votes from right-leaning and religious parties to prevent Netanyahu from winning a third term.
‘I decided to fight in my field, the political field, so that he, perhaps, would not have to fight in his field, the battlefield.’
“The only thing that Livni is capable of doing is splitting the ‘left’ bloc, not increasing it,’’ Aviad Kleinberg, a professor of history at Tel Aviv University, wrote in a column in Tuesday’s Yediot Aharonot newspaper.
Livni’s long-awaited announcement came the day after Netanyahu’s Likud Party completed a primary in which several moderate members were pushed toward the bottom of the list, with little hope of election, beaten out by ultranationalist candidates including Moshe Feiglin. That rightward trend, some commentators said, could have a more fundamental effect on the campaign dynamic, leaving some centrist Likud voters shopping for alternatives.
To Nahum Barnea, the dean of Israel’s columnists, the primary showed Likud had ‘‘gone off the rails’’ and provided Livni with a ‘‘good starting point.’’
‘‘For the first time since elections were announced, it now seems as if there is no certainty that their results are a foregone conclusion,’’ Barnea wrote, also in Tuesday’s Yediot. ‘‘Netanyahu is going to have to persuade the voter that he is going to form a responsible, levelheaded government for everyone.’’
Livni, a Tel Aviv-born lawyer and mother of two, was first elected to Parliament in 1999, with Likud, and served in several ministerial posts under former prime minister Ariel Sharon before becoming Ehud Olmert’s foreign minister in 2006.
Under her leadership, Kadima in 2009 won the most seats in Parliament — 28 to Likud’s 27 — but she failed to form a government and refused to join Netanyahu’s. She headed the opposition for three years, until her ouster in internal Kadima elections this spring.
Unlike the current leading left-center candidates — Shelly Yachimovich of the Labor Party and Yair Lapid of There is a Future — who are emphasizing internal Israeli matters of socio-economics and identity, Livni’s campaign is likely to center on the Palestinian conflict and other security issues.
On Tuesday, Livni harked back to her entry into politics in 1995, when, she said, she looked at her 5- and 8-year-old sons and ‘‘decided that it was my duty to act in order for them to stay, after me, in a safe country.’’ She said she consulted her boys — now young men — again this fall, and they told her to ‘‘fight for us.’’
As the younger son, a paratrooper, headed south as part of Israel’s air campaign on the Gaza Strip last week, Livni said she sent him a text message saying ‘‘that I decided to fight in my field, the political field, so that he, perhaps, would not have to fight in his field, the battlefield.’’