"Nissenkorn has chosen a new political home and is therefore expected to resign," Gantz said. "The justice portfolio is one of Blue & White’s most important assets to safeguard democracy and the rule of law, and we will continue acting the same way we have thus far."
Earlier Tuesday, Nessenkorn announced he intended to join forces with Tel Aviv Mayor Ron Huldai who is expected to announce on Tuesday he is forming a party to run in the next ballot.
"We will bring a message to hundreds of thousands of Israelis who feel they have no political home - and we will do so through actions and not through words," Nissenkorn said.
Blue & White lambasted Nissenkorn for his decision to jump ship ahead of the next election.
"Nissenkorn proved he cares only about himself first and foremost. He did not even have the courage to leave the party properly and resign. Huldai, watch your back," a statement read. "Nissenkorn is being ungrateful and is acting like a wheeler-dealer rather than a leader. Benny Gantz appointed him, backed him all the way... In the end, [Nissenkorn] made a personal decision and turned his back on [Gantz]."
Nissenkorn's decision to depart the centrist party reportedly stemmed from Gantz's intentions to join forces with Naftali Bennett's right-wing Yamina party.
Meanwhile, Foreign Affairs Minister Gabi Ashkenazi was also reported to announce a temporary hiatus from politics ahead of the upcoming general vote.
Huldai, who is slated to launch his parliamentary run Tuesday evening, is not expected to resign for the time being from his position as mayor of Tel Aviv, and reserve the option to continue at his post until 2023 if he fails to enter Knesset.
Gantz is also expected to speak to the public at 8pm Tuesday and announce his run as the head of Blue & White.