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Sen. Ted CruzTed CruzWarren builds her brand with 2020 down the road Trump wall faces skepticism on border No Congress members along Mexico border support funding Trump's wall MORE (Texas) is firing back at Sen. John McCain (R-Ariz.) for suggesting there are questions about Cruz's eligibility to run for president.
Cruz brushed off McCain's suggestion that it was "worth looking into" the issue, saying the 2008 GOP nominee is simply trying to help Sen. Marco RubioMarco RubioTop Trump officials push border wall as government shutdown looms Rubio defends Trump: 'This whole flip-flop thing is a political thing' Rubio: Shutdown would have 'catastrophic impact' on global affairs MORE (R-Fla.) win the Republican nomination.
"I think it is no surprise to anybody that John McCain is going to be supporting Marco Rubio in this election," Cruz told Bloomberg's Mark Halperin on "With All Due Respect."
"It's no surprise at all that he's trying to do what he can to help the candidate that he's favoring who he thinks shares policy positions with him," Cruz added.
McCain, who faced similar eligibility questions during his 2008 bid, argued during a local radio program in Arizona on Wednesday that there is a difference between him and Cruz.
Cruz was born in Canada to an American mother. McCain was born on a U.S. military base in Panama.
"So I think there is a question. I am not a Constitutional scholar on that, but I think it’s worth looking into. I don’t think it’s illegitimate to look into it," McCain said.
Cruz has argued that he is eligible for the presidency and a "natural born citizen" as stipulated by the Constitution after rival Donald Trump questioned his eligibility on Tuesday.
McCain had endorsed Sen. Lindsey Graham (R-S.C.) for president, but Graham dropped out of the race last month after failing to gain traction in the polls.
Cruz and McCain have clashed frequently in the Senate, with McCain once calling Cruz and Sen. Rand Paul (R-Ky.) "wacko birds."