Story highlights Marco Rubio says Ted Cruz's attacks over immigration are about calculation, not consistency

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Washington (CNN) Marco Rubio says Ted Cruz's attacks over immigration are about political calculation, not consistency, because Cruz, too, has changed his positions.

Rubio unleashed an attack on his Republican presidential foe Sunday on ABC's "This Week" -- the latest episode in a series of exchanges between the two freshman senators.

"When it comes to Ted, he has changed his position on immigration all over the place," Rubio said.

"I mean, he used to be against birthright citizens -- or he used to be for birthright citizenship; now he says he's against it," he said. "He used to for legalizing people that were here illegally. Now he says he's against it. He used to be for a 200% increases in green cards, doubling them; now he says he wants none. And he said he used to be for a 500% increase in guest workers. And now he says he wants zero."

Rubio added: "So this is not consistency; this is calculation as he's changed his position on these issues as we get closer to Election Day."

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