Cruz has steadfastly maintained that President Barack Obama’s administration would become a leading state-sponsor of terror if the agreement it struck with Iran makes it past Congress. He and others have argued that Iran would use a windfall from sanctions relief to finance terror abroad.

Both Obama and Romney have called Cruz’s remarks inappropriate.

Romney wrote on Twitter early Thursday that he also opposes the Iran deal, but said Cruz’s comments were “way over the line on the Obama terrorism charge. Hurts the cause.”

Cruz, 2016 presidential candidate, fired back at Romney in a Thursday radio interview with KFYO’s Chad Hasty.

“So Mitt Romney’s tweet today said, ‘Gosh, this rhetoric is not helpful,'” Cruz said. “John Adams famously said, ‘Facts are stubborn things.’ Describing the actual facts is not using rhetoric; it is called speaking the truth.”

The senator recalled what he described as a critical moment during the 2012 presidential race: A back-and-forth over that year’s attack on a diplomatic facility in Benghazi, Libya.

“Part of the reason that Mitt Romney got clobbered by Barack Obama is because we all remember that third debate where Barack Obama turned to Mitt and said, ‘I said the Benghazi attack was terrorism and no one is more upset by Benghazi than I am.’ And Mitt, I guess listening to his own advice, said, ‘Well gosh, I don’t want to use any rhetoric. So OK, never mind. I’ll just kind of rearrange the pencil on the podium here,'” Cruz said.

He added that the 2016 presidential candidates need to speak up or they will fail like Romney.

“We need to stand up and speak the truth with a smile,” he said. “The truth has power and every time we have Republicans who shy away — who don’t want to engage, who don’t want to speak the truth — we lose.”