Former defence minister Amir Peretz, a stalwart of Israel's Labour party, has jumped ship to join the new party of former foreign minister Tzipi Livni ahead of a January vote, Livni announced on Thursday.
"The lawmaker and (former) defence minister Amir Peretz has taken the brave decision to join my side," Livni said at a surprise news conference shortly before the deadline for parties to submit final lists for January 22 elections.
Livni once led Israel's main opposition party Kadima, but resigned from parliament in May a month after she lost leadership of the centre-right faction to challenger Shaul Mofaz.
Just last week, she announced her return to politics at the helm of a new party called The Movement.
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Despite her rightwing background -- Livni once belonged to the Likud party now lead by Israeli Prime Minister Benjamin Netanyahu -- the former foreign minister has been cast as an increasingly moderate politician.
She has spoken publicly about the need for a peace agreement with the Palestinians, and criticised Netanyahu's government for its approach to the issue.
"I believe we need to reach a just agreement (with the Palestinians) in a responsible and sober manner, which will preserve Israel as Jewish and democratic," she said in announcing her new faction.
"Israel is going into an election with many people, like me, feeling that Israel's situation is deteriorating. There is no personal or ideological alternative to the prime minister, and there is no one who represents our positions on the most critical issues facing Israel," she said.
Peretz's defection comes despite the fact that Labour party elections at the end of November awarded him the third place position on the faction's list for the January 22 general election.
But the long-time politician had also taken issue with the political agenda being advanced by Labour leader Shelly Yachimovich, who has prioritised economic and social issues over the peace process and declined to rule out joining a coalition government with Netanyahu.