US President Barack Obama's comments today, saying Republican candidate Donald Trump "will not be president", follow yet another day of name-calling on the US Republican campaign trail.
"I've never seen a human being lie so much," said Mr Trump. "He lies about everything."
It was another "pants on fire" day in South Carolina as both Mr Trump and Marco Rubio accused Ted Cruz of being dishonest.
"I hate to say it about the person, but during the debate Rubio called him a liar so I felt a lot better," said Mr Trump.
"He's spent the last two weeks literally making stuff up," said Mr Rubio.
"Both Donald Trump and Marco Rubio have this very strange pattern where if you point to their actual record, if you point to the words that come out of their mouth, they don't respond on substance; they scream and shout 'liar, liar, liar'," said Mr Cruz.
In a lengthy Facebook post, Mr Trump contended Mr Cruz misled voters by quoting Mr Trump's past positions on abortion and healthcare. Mr Trump now describes himself as pro-life and against Obamacare.
Mr Rubio claims Mr Cruz distorts on many fronts.
"He didn't tell the truth about Ben Carson in Iowa, and he's not telling the truth about my position on marriage, on Planned Parenthood," said Mr Rubio. "He even had an ad pulled down from the stations because they were untrue."
Mr Trump has also questioned Mr Cruz's mental health.
"Ted Cruz is desperate," said Mr Trump. "I think Ted's a very unstable guy."
Mr Cruz called for increasing the size of the US military in a speech aboard the USS Yorktown. He was asked about Mr Trump's "unstable" charge as he walked off the World War II aircraft carrier.
"The reason Donald insults is because he can't defend the substance," said Mr Cruz. "He can't dispute the substance because it's his own word."