Former Defense Minister Moshe Ya'alon spoke about the appointment of Esther Hayut as Supreme Court Chief Justice.
Hayut replaces Miriam Naor, who retired on Thursday.
"The current situation is challenging, with serious internal threats to Israel's democracy," Ya'alon said. "This is a battle for the State of Israel's image and future."
"I share Hayut's worries, and support President Reuven Rivlin's message. I fear the continued damage to Israel's basic values and its character as a Jewish and democratic state. This is a recipe for dictatorship, not democracy."
On Monday, Rivlin said he "can only describe what I see in what appears to be an ongoing attempt to weaken the gatekeepers of Israeli democracy."
Ya'alon also slammed Israeli Prime Minister Binyamin Netanyahu, claiming that "the Prime Minister is purposely de-legitimizing the gatekeepers, to ensure his political survival," he said. "The President's term 'after the flood,' describes it well. Netanyahu is acting not for the good of the country, but for his own survival."
Regarding the proposed law to forbid investigation of a sitting prime minister, Ya'alon said it was "easy to see who had proposed the law." The law, however, was not intended to be in effect during this Knesset.
"These are Netanyahu's representatives. Why else would such a thing be proposed right now? You think it's coincidence? The siege around Netanyahu is tightening, the public sees the smoke, and I see the fire. These are initiatives which are meant to save Netanyahu's skin. He's just trying to buy time."
Police are looking into gifts from wealthy supporters of Netanyahu and suspicions he sought a secret deal with Arnon (Noni) Mozes, the publisher of leftist newspaper Yediot Aharonot.
Will Ya'alon run in Israel's next elections?
"I'm trying to build my political strength," he said. "We'll meet everyone, we'll think what we need to do and how to do it, either together or separately. I prefer to work together."
Ya'alon formed his own political party in March, announcing his intention to run for Prime Minister in the next elections. However, a poll showed Ya'alon's party struggling to pass the four-seat threshold required for entry into the Knesset. Ya'alon was fired from his position as Defense Minister by the Prime Minister and has been attacking him since then.