Feud Goes Nuclear as Trump Repeatedly Calls Cruz 'Unstable'

Donald Trump stood by his slams of Sen. Ted Cruz (R-Texas) as "unstable" after calling his rival a "basket case" at a South Carolina press conference.

Trump told CNN after Monday's presser that he was reacting to Cruz noting his changed positions including on abortion and an assault weapons ban.

"He knows what the answer is and he chooses just not to say it. I mean, he's just -- and he clearly understands that he's lying. You know, he's an unstable guy. I've watched him and I find him to be a very unstable guy," Trump said.

"What I do in life is ideal with many, many people. I built a great company and I understand stability. He's a very unstable person. I think maybe because of, you know, the pressure of the campaign. I don't know exactly what it is. But he'll take something like Obamacare where I'm totally and absolutely, you know, going to repeal and replace Obamacare from its inception and he'll say that I love Obamacare, which is so ridiculous."

Cruz said Trump had "apparently lost it," adding that his poll numbers had "rattled" Trump.

“Donald Trump just can’t handle the truth,” Cruz communications director Rick Tyler added in a statement. “He believes everyone who disagrees with him is lying.  But everything Ted Cruz has said is accurate because he’s using Trump’s own words. If Trump doesn't like what's been said, he only has himself to blame.”

Asked about Cruz calling him "rattled," Trump said, "He doesn't mean that. He says that just for effect. He's the one. I mean, he's an unstable guy."

"You watch him and watch the way that he behaves. I find him to be very much that way. He's just using that expression because he likes it. You know, it's just ridiculous. I'm not one that gets rattled, believe me," he added. "...Ted Cruz has no clue as to how to make America great again. He has not employed virtually a person in his life, I mean, maybe a secretary."

"...So, he's a very bad guy, he's a very nasty guy. He's got no endorsements from any senators who he works with. He'll never be able to unify anything. And, frankly, he'll never get any support from anybody. Even the people that are very conservative, strongly conservative aren't giving him their support. So, he can stand in the middle of the Senate floor and let everybody laugh at him, which is what happened the last time, you know. He got nothing out of it, zero. But, you know, that's not the kind of person that you need to turn the country around."

The campaign also got a bit more nuclear between Cruz and Sen. Marco Rubio (R-Fla.), with both camps sending out lists Monday of what they deemed lies from their opponents. Rubio's list title: "Cruz BusTED on Lies: Cruzin' Toward New Lows."