Republican presidential candidates Donald Trump and Texas Sen. Ted Cruz participate in the Fox Business Network GOP debate at the North Charleston Coliseum and Performing Arts Center Thursday in North Charleston, South Carolina. Getty Images

A Texas lawyer fulfilled Donald Trump's prophecy when he filed a lawsuit Friday raising questions about whether Ted Cruz is eligible to run for president. Newton Boris Schwartz, an attorney based in Houston, was suing the Texas senator over a stipulation in the Constitution that requires candidates to be natural-born citizens of the United States, the Hill reported. Cruz was born in Canada, but his mother is American.

Schwartz asserted Friday that the federal court system needed to hammer out the definition of "natural-born." Otherwise, he alleged, Cruz was not qualified to run for president. “This 229-year-old question has never been pled, presented to or ... resolved by the U.S. Supreme Court,” Schwartz wrote, according to Bloomberg. “Only the U.S. Supreme Court can finally decide, determine judicially and settle this issue now.”

Cruz's citizenship was at the center of one of the most heated moments of the sixth GOP primary debate, held Thursday night in North Charleston, South Carolina. Front-runner Trump challenged Cruz, who was in second place among the candidates, over his citizenship. "If ... he beats the rest of the field, I already know the Democrats are going to be bringing a suit. You have a big lawsuit over your head while you're running," the billionaire businessman said. "And if you become the nominee, who the hell knows if you can even serve in office?"

Cruz fired back that he did not want to take legal advice from Trump, who admitted to attacking the senator because of his recent rise in popularity. Trump said in September that Cruz's birthplace was not an issue.

"Since September, the Constitution hasn't changed. But the poll numbers have," Cruz added. "The facts and the law here are really quite clear. Under longstanding U.S. law, the child of a U.S. citizen born abroad is a natural-born citizen."

Schwartz wasn't so sure, so he filed the court documents. “The country will be in chaos if he’s elected president or vice president and this goes to trial then,” the attorney told Bloomberg. “I can see both sides of this argument.”

The Huffington Post reported that more lawsuits were expected to come as Cruz's campaign continues.