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Presidential candidate Sen. Ted Cruz is doubling down on his criticism of the Iran deal and is firing back at former Massachusetts Gov. Mitt Romney and former Florida Gov. Jeb Bush, both fellow Republicans who assailed the Texas lawmaker for his rhetoric on the nuclear agreement.

On the Chad Hasty radio show on Thursday, Cruz said Romney, who ran for president in 2012, and Bush, who is running for president, are too afraid of speaking the truth about the Iran deal, "'talking about ‘now take it easy guys you don’t really need to oppose this Iranian nuclear deal quite so forcefully.’”

"One of the reasons Republicans keep getting clobbered is we have leaders like Mitt Romney and like Jeb Bush who are afraid to say that," Cruz said.

On Thursday, Romney took to Twitter to criticize Cruz for saying he believed the Iran nuclear deal would give Iran $100 billion, which would find its way into the hands of terrorist groups like Hamas and Houthis that he said are backed by Iran.

“If this deal goes through, the Obama administration, President Obama, Hillary Clinton, John Kerry, will become the leading global financiers of radical Islamic terrorism,” said Cruz during a roundtable discussion on Tuesday.

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To which Romney responded:

During the nearly 20 minute interview Cruz went on to call out Bush, who also criticized Cruz for his rhetoric.

Cruz went on to defend presidential candidate Mike Huckabee’s comments in which he said Obama and his Iran deal are marching Israel “to the door of the oven” – a reference to the Holocaust.

"I thought it was really unfortunate in the past couple weeks to see Jeb Bush number one, attacking Mike Huckabee for speaking out about the incredible threat a nuclear Iran poses to Israel,” Cruz said.

He re-emphasized that he agreed with Israeli Prime Minister Benjamin Netanyahu that a nuclear Iran is an existential threat to Israel.

“The Iranian nuclear deal is catastrophic,” Cruz said. “Describing the actual facts is not using rhetoric — it’s speaking the truth.”