Israel's former defence minister Shaul Mofaz won a commanding victory on Wednesday, becoming head of the opposition, but there are serious doubts about whether he can reverse Kadima's dwindling fortunes.
Officials with the centre-right party said Mofaz had taken 61.77 percent of the votes cast on Tuesday, easily beating his rival, incumbent faction leader Tzipi Livni, who took just 37.23 percent of the vote.
The bitterly-fought leadership contest ended Livni's three-and-a-half year reign as faction chief, and was a chance for Mofaz to reverse the results of the party's last primaries, which saw him lose to his rival by just a few hundred votes.
But turnout during Tuesday's primary was low, with just 41 percent of the party's 95,000 registered members voting, as a flurry of recent polls showed Kadima may lose up to half its 28 seats in the next elections which are due within 18 months.
Speaking to reporters as he cast his vote on Tuesday, Mofaz sounded a confident note, saying he was ready to take on Prime Minister Benjamin Netanyahu and his rightwing Likud party.
Elections are officially tabled for October 2013, but rumours of an early election are rife, with observers speculating they could take place before the end of this year.
"At the end of this day, Kadima will set out on a new path as an alternative to the poor government of Netanyahu. I intend to win at the general elections and to replace Netanyahu," he said.
But commentators said it was not clear whether Mofaz could reverse Kadima's fortunes.
Sima Kadmon, writing in Yediot Aharonot, said Mofaz would have to ensure Kadima was a real alternative to Likud, something Livni was criticised for failing to do.
"His outspoken statements against the prime minister were intended to differentiate himself and turn himself into an alternative. Mofaz will have to work hard in order to prove that he is capable," she wrote.
"Netanyahu hoped for Livni's victory," Ben Caspit wrote in the Maariv daily, saying Mofaz had the potential to take seats from Likud, enlarging the centrist bloc in the Knesset "to the point of a political upheaval."
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"But this is already wild speculation," he acknowledged.
"As of this morning, Mofaz has to reunite Kadima, make it clear to Livni's MPs that there are no contracts on their heads -- and try to keep Livni herself."
Commentators suggested Livni was likely to leave Kadima after her defeat, and might even retire from politics altogether.
"It is clear to everyone who knows Livni that with such results she will not stay," Kadmon wrote. "She truly believes that she should only be there if she can lead."
In his victory speech, Mofaz reached out to his rival, urging her to "join us in this battle," saying: "Tzipi, your place is with us."
But while Livni phoned to congratulate Mofaz, she did not offer him any public support.
"These are the results. I thank all the members of Kadima who gave me their confidence and their support," she said.
Livni's defeat was the coda to a fall from grace for the former foreign minister, who had been considered as the most powerful woman in Israel and had harboured ambitions of becoming the country's second female premier.
She was among the first ministers to leave Likud for Kadima in 2005, when former premier Ariel Sharon formed the party after his controversial decision to pull all settlers and troops out of Gaza.
She led the party to victory in the 2009 elections, when Kadima won more seats than any other faction, but was unable to form a coalition and opted to stay in opposition rather than join Netanyahu's government.
The Iranian-born Mofaz is a relative political novice, known for his military background and tenure as defence minister, though he currently heads the powerful parliamentary committee on foreign affairs and defence.
He is considered a hardliner who led a huge invasion of the West Bank in 2002.
The former minister has taken a tough stance on Iran, but was also charged with leading Israeli troops out of Lebanon and Gaza.