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A veteran attorney in Ted Cruz's hometown of Houston has filed a federal lawsuit challenging the Canadian-born senator's eligibility to be president.

In a 28-page complaint Thursday, Newton Schwartz asked the Supreme Court to decide if Cruz's birth to an American mother and Cuban father while they lived in Calgary violates the Constitution's "natural born citizen" requirement.

Cruz argues that because his mother is American, he became a U.S. citizen at birth. But the Supreme Court hasn't previously considered the eligibility question.

Presidential rival Donald Trump has repeatedly questioned Cruz's presidential eligibility.

The pair squared off during Thursday night's Republican debate. When Trump again raised the issue, Cruz shot back that though the Constitution hasn't changed recently, his polling numbers have — driving Trump's "birther" questions.