Labor party members on Monday offered their praise for freshly elected party chairman Avi Gabbay, after his surprise victory over veteran lawmaker Amir Peretz, describing it as a fresh start for the left-leaning party that has long-languished in the political doldrums.

Conceding defeat, Peretz said in a tweet that he called Gabbay “to congratulate him on being elected to the position of Labor Party leader and its candidate for prime minister.”

In a show of unity, Peretz said that he and his supporters “will stand by his side and help him to return the Labor party to power.”

Incumbent party chairman Isaac Herzog, who was bounced out of the leadership contest after finishing third in the first round of voting last week, congratulated Gabbay on his victory and said he would work with him to help return the party to power.

“I made it clear to [Gabbay] that I will stand by his side to help strengthen the party and replace the government,” Herzog tweeted, after having supported Peretz in the runoff.

Supporters of Avi Gabbay celebrate in Tel Aviv after he was elected leader of the Labor party on July 10, 2017. (AFP Photo/Jack Guez)

Supporters of Avi Gabbay celebrate in Tel Aviv, after he was elected leader of the Labor party on July 10, 2017. (AFP Photo/Jack Guez)

Tzipi Livni, whose Hatnua party makes up the Zionist Union faction along with Labor, said Gabbay’s victory marked an optimistic turning point for the party.

“The shared mission between us at the moment is to produce renewed and true hope for replacing the government and to offer a new way, [that is] better for Israel and its citizens,” Livni said in a statement.

“Now that the Labor party has finished its democratic process, we must together turn to the public and widen the ranks of a large bloc that will be an address for the same tremendous public in Israel, that believes in our way and is striving to replace the government and its path,” she added.

Labor MK and Gabbay supporter Stav Shaffir also offered her praise for the party’s newly elected chairman, describing it as a fresh chance for the party.

“Victory! The start of a new way,” she tweeted.

Former prime minister Ehud Barak — the last Labor leader to serve as premier — said Gabbay’s election as the party’s new leader is evidence of “a revolution” within the party.

“Members wanted victory,” he said in a tweet. “Bibi is sweating, and rightfully so.”

Avi Gabbay arrives to a polling station in Tel Aviv on July 10, 2017. (Miriam Alster/Flash90)

Avi Gabbay arrives to a polling station in Tel Aviv on July 10, 2017. (Miriam Alster/ Flash90)

In addition to Labor party leaders, a number of other politicians offered their praise for Gabbay following his victory.

Yesh Atid chairman Yair Lapid welcomed Gabbay as Labor’s new leader, saying the Israeli political landscape “needs good people.”

“I am glad that Gabbay decided to contribute his knowledge and experience to the citizens of Israel,” he said in a video message posted on Twitter.

The leader of the right-wing Jewish Home party Naftali Bennett wrote on Twitter that he spoke with Gabbay on the phone after his win, saying that he congratulated the former Kulanu party minister on his victory, which “expresses the desire of the Labor party members for renewal.”

Taking 52.4 percent of the vote compared to Peretz’s 47.6, Gabbay came from a near-2,000 vote deficit in the first round of the primary that was held last week to win, getting 16,080 votes compared to 14,734 votes for Peretz.

Amir Peretz (R) and Avi Gabbay (L). (AFP Photo/Jack Guez and Ozan Kose)

Amir Peretz (R) and Avi Gabbay (L). (AFP Photo/Jack Guez and Ozan Kose)

Gabbay’s victory sees him immediately taking the post of party leader, but he cannot be the Knesset opposition head, as he is not a sitting Knesset member. He must pick a lawmaker for that position, and a majority of opposition MKs must approve his choice. He has said that he will keep Herzog in the position.

Herzog’s downfall as party leader came after he alienated many of his party members in holding secret coalition negotiations with Netanyahu in 2016, which fell apart in May of that year. Since then, the opposition leader has advocated other center and left-wing parties to forge a bloc to oust Prime Minister Benjamin Netanyahu from power, though parties such as Yesh Atid have demurred.

The primaries came after Labor had plummeted over the past year in opinion polls, receiving a projected 10-12 seats (combined with the Hatnua party that makes up the Zionist Union faction), down from its current 24 seats.

Gabbay’s leadership will likely determine whether the center-left party, plagued by internal divisions, is able to become the main challenger to Netanyahu’s Likud in the next elections, and, consequently, whether it could seize the premiership.

Meanwhile, the centrist Yesh Atid party appears to have wooed most of Labor’s voters, climbing steadily in surveys, and at this point poised to become the top contender against Likud, according to the polls.

Times of Israel staff contributed to this report.