Cruz tweeted a famous scene of Henry Winkler's "Happy Days" character, Fonzie, "jumping the shark" late Tuesday.
Earlier in the day, The Washington Post released an interview with Trump in which the GOP front-runner called Cruz's Canadian birthplace a "very precarious" issue for Republicans if they were to nominate Cruz.
"Republicans are going to have to ask themselves the question: 'Do we want a candidate who could be tied up in court for two years?' That'd be a big problem," Trump said, according to The Post. "It'd be a very precarious one for Republicans because he'd be running and the courts may take a long time to make a decision. You don't want to be running and have that kind of thing over your head."
"I'd hate to see something like that get in his way. But a lot of people are talking about it and I know that even some states are looking at it very strongly, the fact that he was born in Canada and he has had a double passport," he added.
Trump has actually been questioning the significance of Cruz's Canadian birth for some time. Early last year, Trump said in an interview that the issue could be a "serious hurdle" for Cruz.
"He was born in Canada. If you know and when we all studied our history lessons, you are supposed to be born in this country, so I just don't know how the courts would rule on it. It's an additional hurdle that he has," Trump said.
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Trump has also been perhaps the most prominent questioner of the authenticity of President Barack Obama's birth certificate. Conspiracy theorists have long raised doubts about Obama's birthplace, suggesting that he was actually born in Africa instead of his native Hawaii.
Cruz's mother was a US citizen when he was born in Calgary in 1970. His father was born in Cuba.
Cruz's campaign declined to comment to The Post.
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