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A firestorm broke out on Capitol Hill Monday over Secretary of State John Kerry reportedly saying Israel could become an "apartheid state," with the No. 2 House leader saying he should apologize and a Republican senator calling on him to resign.

By the end of the day, though, the secretary was edging away from his comments. While defending his support for Israel, he said "apartheid" is a word "best left out of the debate here at home."

"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 said.

Kerry stressed that he does not consider Israel an apartheid state, and: "Anyone who knows anything about me knows that without a shred of doubt."

Kerry released the statement in an apparent effort to temper a rapidly growing controversy involving criticism from both sides of the aisle.

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    House Majority Leader Eric Cantor earlier urged Kerry to "apologize to the Israeli government and people."

    "Reports that Secretary Kerry has suggested Israel is becoming an apartheid state are extremely disappointing," Cantor, who is Jewish, said in a statement. "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."

    Late Monday, Sen. Barbara Boxer, D-Calif., added a bipartisan note to the Kerry criticism, tweeting, "Israel is the only democracy in the Middle East and any linkage between Israel and apartheid is nonsensical and ridiculous."

    At the same time, Sen. Mark Begich, D-Alaska, issued a statement saying, “I am disappointed with Secretary Kerry’s reported remarks...(he) knows as well as anyone that negotiating lasting peace in this region of the world is difficult but it’s not productive to express his frustration in this way."

    The backlash follows a Daily Beast report claiming Kerry made the statement during a closed-door meeting Friday with "influential world leaders." He reportedly warned that if Israel doesn't make peace, the country could become "an apartheid state."

    Shortly after Cantor’s call for an apology, Texas GOP Sen. Ted Cruz called for Kerry’s resignation on the Senate floor.

    "Mr. President, it is my belief that Secretary Kerry has thus proven himself unsuitable for his position and that before any further harm is done to our alliance with Israel, he should offer President Obama his resignation,” Cruz said. “And the president should accept it.”

    Kerry reportedly made the comparison after peace talks hit a wall last week, as Fatah announced a unity agreement with Hamas. Israel, which like the U.S. considers Hamas a terror group, suspended peace talks after that announcement -- although Kerry continued to voice hope that both sides could return to the negotiating table.

    Sen. Marco Rubio, R-Fla., a member of the Senate Foreign Relations Committee, also slammed Kerry over the reported remarks, made ahead of Holocaust Remembrance Day.

    "These comments are outrageous and disappointing," he said in a statement. "Incendiary name calling does not change the fundamental fact that Israel does not currently have a viable partner for peace. I urge Secretary Kerry and the administration to focus on pressing challenges in the Middle East such as ending the humanitarian catastrophe in Syria and preventing Iran from acquiring a nuclear weapon instead of pressuring Israel to make additional concessions to partners who have now chosen to align themselves with a terrorist group."

    The State Department is not denying that Kerry made the remarks. Spokeswoman Jen Psaki, asked about them at Monday's briefing, said she would not confirm comments made during a private meeting.

    While not confirming whether Kerry warned that Israel could become an apartheid state, she said: "The secretary does not believe and did not state publicly or privately that Israel is an apartheid state, and there's an important difference there."

    "Israel is obviously a vibrant democracy with equal rights for all of its citizens," she said, reiterating that Kerry believes a "two-state solution is the only way to have two nations and two people living side-by-side in peace and security."