“I don’t know, to be honest, and I like him a lot,” Trump said about Cruz’s citizenship in an interview on CNN’s “The Situation Room with Wolf Blitzer.”
Trump doubled down on his recent attacks, questioning the Canadian-born hopeful’s eligibility to be president. But the real estate mogul explained that he’s discussing the topic because reporters have brought it up.
He suggested Cruz go “immediately” to federal court and seek a “declaratory judgment” to quell the issue. 
“You go to federal court, you ask for a declaratory judgment. Once the court rules, you have your decision,” Trump said. “That will clear it all up."
Trump defended his remarks, saying that he's looking out for the Texas senator.
“If Ted should eek it out, and I hope that doesn’t happen, and he’s got this cloud over his head, I don’t think it’s possible for him to do very well," he said. 
“I’m doing this for the good of Ted. We have a good relationship.” 
Trump has revived birther claims aimed at Cruz, saying it could be a “very precarious” issue for his rival. He is stepping up his attacks on Cruz less than a month out from the Iowa caucuses, as the Texas senator leads in polls in the first-in-the-nation caucuses.
Cruz’s camp responded to the claims Tuesday by tweeting the famed “jumping the shark” clip from the television show “Happy Days,” suggesting the claim is desperate.
Before declaring his candidacy, Trump had brought up the “birther” argument against Cruz in March, saying that the senator’s birthplace was “a hurdle.”
The billionaire businessman has also questioned President Obama’s eligibility to be commander in chief for years.