The Texas Republican is upset with comments the secretary of State made at a closed-door meeting.
Sen. Ted Cruz wants Secretary of State John Kerry to resign over his comment that without a two-state solution to the Israeli-Palestinian conflict, Israel risks becoming an "apartheid state."
The Texas Republican, who's possibly running for president in 2016, took to the Senate floor Monday to call for Kerry to step down.
"Sadly, it is my belief that Secretary Kerry has proven himself unsuitable for the position he holds," Cruz said. "Therefore, before any further harm is done to our national security interests and to our critical alliance with the nation of Israel, that John Jerry should offer President Obama his resignation and the president should accept it."
Kerry's remarks, made in a closed-door meeting with world leaders and captured on audio obtained by The Daily Beast, warned of the consequences of failing to reach a resolution to the Israeli-Palestinian conflict:
A two-state solution will be clearly underscored as the only real alternative. Because a unitary state winds up either being an apartheid state with second-class citizens—or it ends up being a state that destroys the capacity of Israel to be a Jewish state," Kerry said. "Once you put that frame in your mind, that reality, which is the bottom line, you understand how imperative it is to get to the two-state solution, which both leaders, even yesterday, said they remain deeply committed to."
Sen. Cruz was one of just three senators to vote against Kerry's confirmation to be secretary of State last January.
The State Department released a statement from Kerry Monday night reaffirming his support for Israel, saying "I will not allow my commitment to Israel to be questioned by anyone, particularly for partisan, political purposes." "Israel," Kerry said, "is a vibrant democracy and I do not believe, nor have I ever stated, publicly or privately, that Israel is an apartheid state or that it intends to become one."
And the secretary addressed his word use explicitly:
I have been around long enough to also know the power of words to create a misimpression, even when unintentional, and if I could rewind the tape, I would have chosen a different word to describe my firm belief that the only way in the long term to have a Jewish state and two nations and two peoples living side by side in peace and security is through a two state solution.
Kerry's initial remarks have sparked other congressional responses. House Majority Leader Eric Cantor called on Kerry to apologize, saying in a statement Monday that "the use of the word 'apartheid' has routinely been dismissed as both offensive and inaccurate, and Secretary Kerry's use of it makes peace even harder to achieve."
President Obama has previously rejected the use of the term "apartheid" to describe the current state of affairs in Israel, saying it's "emotionally loaded, historically inaccurate, and it's not what I believe."
And the powerful American Israel Public Affairs Committee called Kerry's remarks "deeply troubling" in a rare statement released Monday.
"Any suggestion that Israel is, or is at risk of becoming, an apartheid state is offensive and inappropriate," AIPAC said. "The Jewish state is a shining light for freedom and opportunity in a region plagued by terror, hate, and oppression."
Matt Berman contributed to this article.