Trump Calls Ted Cruz Unstable, Liar -- Threatens to Sue

"He doesn't even have the right to serve as president or even run as president."

Presidential candidate Donald Trump held a press conference on Monday and called his opponent Senator Ted Cruz an "unstable person" and a "liar" and threatened to sue him for being ineligible to run for president. Trump wants Cruz to "take down his false ads and retract his lies."

Cruz was having none of it:

But Cruz fired back, saying the real estate mogul "apparently lost it," shouting "liar, liar" like a grade school student and claimed that "internal poll numbers in South Carolina must be plummeting following that debate."

What got Trump so upset? The reality show star claims that Cruz "printed lies" about his record on abortion, the Second Amendment and potential Supreme Court picks.

"For instance, he talks about me being against the Second Amendment," Trump said during a press conference in Hanahan, SC. "I am the strongest person running in favor of the Second Amendment. I'm a member of the NRA, my sons have been long-term members of the NRA and they're extraordinary shots."

Unless he gets an apology, Trump will file suit.

“He'll apologize but I don't want an apology after the election, I want the apology before," Trump said. "If he doesn't, I'm going to bring a lawsuit because in my opinion based on what I've learned over the last two or three days from very top lawyers, he doesn't even have the right to serve as president or even run as president. He was born in Canada. So I will bring that lawsuit if he doesn't apologize.”

Cruz addressed those comments at an event on Monday, saying Trump has "lost it."

“I think the people of South Carolina deserve a campaign focused on issues, and substance, and record. But I will continue pointing out the truth about records,” said Cruz to a crowd in Camden, South Carolina.

“It is not a response simply to start yelling louder and louder ‘liar, liar, liar’ whenever anyone points to the candidate’s own record. Truth matters. And we are not in grade school where you just get to say ‘liar, liar, pants on fire’ and not respond to the substance.”