Former Labor party leader Amir Peretz and ex-Kulanu minister Avi Gabbay on Tuesday advanced to the second round in the party’s leadership race, in an upset that saw incumbent Isaac Herzog unseated from power after a tumultuous four years at the helm.

Peretz was in the lead with 32 percent (10,141 votes), followed by newcomer Gabbay with 27% (8,395), as the polls closed on Tuesday evening. The two top contenders will face off next Monday, since no single candidate received the required 40% of the vote in Tuesday’s first round to declare a winner.

Herzog, the party leader since 2013, received just 16.7% of the vote (5,204), with Labor MK Erel Margalit close behind at 16.1% (4,997). Labor MK Omer Bar Lev received just six percent.

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The turnout in the primary stood at 59%, or 30,998 Labor voters.

In a statement on Tuesday evening, Herzog congratulated Gabbay and Peretz and thanked his followers.

“The members of the Labor party have spoken. I respect their decision,” said Herzog.

Peretz, a former defense minister who led the party as a junior coalition party under Kadima over a decade ago, has been campaigning vigorously for the post since December.

“I am proud of my accomplishment and am convinced I will win in the second round, after which we will replace Netanyahu,” said Peretz on Tuesday.

Gabbay, meanwhile, was seen as the dark horse in the race, bringing fresh blood and a right-wing political history to the traditionally dovish party.

“Wow,” he wrote on Twitter on Tuesday night, an hour after the results were announced.

In a speech to supporters late Tuesday, he vowed to battle to ensure Labor is able to form a governing coalition in Israel, “not join a coalition” — a reference to intermittent coalition contacts between Herzog and Prime Minister Benjamin Netanyahu which ultimately led nowhere.

A former minister in Netanyahu’s government, Gabbay quit in May 2016, after coalition talks brought the Yisrael Beytenu party into the government with a dramatic tirade accusing the coalition of leading Israel on a path to destruction.

The breakout moment for Gabbay, a relatively unknown minister who was not elected to Knesset, but rather appointed as an external candidate by party leader Moshe Kahlon, was followed by his crossing the political aisle and joining the fight for the Labor leadership

Gabbay claims to have brought thousands of new members to the Labor party. However, since he is not a sitting Knesset member, Gabbay would likely not be permitted to serve as opposition leader should he win.

Herzog 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 come after Labor has 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.

The winner of the leadership bid will likely determine whether the center-left party, plagued by internal divisions, is able to become the main challenger to Prime Minister Benjamin 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.