Opposition leader and Zionist Union head Isaac Herzog is not ruling out the possibility of joining Prime Minister Benjamin Netanyahu's government on the backdrop of the rift between the prime minister and Education Minister Naftali Bennett, a senior official in the Zionist Union faction said on Sunday.

Bennett, who heads the right-wing Habayit Hayehudi party, is threatening to veto Avigdor Lieberman’s appointment as defense minister as his party and Likud have yet to resolve their differences over Bennett’s demands to reform the security cabinet.

Speaking of the need to reform the security cabinet, Bennett vowed earlier Sunday that he "will continue to defend Israel's soldiers whether we are part of the government or not."

Herzog's Zionist Union faction is waiting to see how the crisis between Netanyahu and Bennett unfolds in the coming days before further exploring the possibility of joining the government. Sources in the Zionist Union claimed that no talks are currently being held with Netanyahu's Likud.

Meanwhile, sources in the Zionist Union also noted that Herzog might instead try to form an alternative coalition and be appointed prime minister in the case that Bennett will follow through with his ultimatum to Netanyahu and remove his party from the governing coalition. This scenario seems unlikely: Herzog will have to unite parties that lack common ground, from right-wing Habayit Hayehudi to the leftist Joint List. However, party members hope that calls for Finance Minister Moshe Kahlon to resign will motivate him to team up with Herzog.

Herzog, on his part, kept quite in recent days and made no indication of his intentions. Sources in the party said this was a calculated move on his behalf designed to increase the tension between Netanyahu and Bennett.

A source in the party said that if Herzog were to publically state that he would not join Netnayahu's coalition, it would strengthen Bennett's position, because Netanyahu would then have no choice to give into Bennett's demands. On the other hand, if Herzog declares that he is considering joining the government, that would strengthen Netanyahu, because Bennett would understand that the prime minister has an alternative to Habayit Hayehudi.