Washington, Oct 1 (IANS): Taking another swipe at Republican presidential nominee Donald Trump's mental stability, Democratic candidate Hillary Clinton on Friday said he was "temperamentally unfit" for the White House.

Speaking at campaign stop in South Florida, Clinton's remark came in the wake of Trump's weight-shaming of former Miss Universe Alicia Machado.

"Why does he do things like that?" Clinton demanded at a rally in Coral Springs, referring to Trump's social-media assault on former beauty queen.

"Who gets up at three o'clock in the morning to engage in a Twitter attack against the former Miss Universe?" she added.

"I mean, his latest Twitter meltdown is unhinged, even for him. It proves, yet again, that that he is temperamentally unfit to be president and commander-in-chief," Clinton said, adding, "I've said it before and I'll say it again, a man who can be provoked by a tweet should not be anywhere near the nuclear codes."

In a series of messages, Trump mocked Machado as a "con," the "worst" and "disgusting". The Republican presidential nominee even claimed that she had appeared in a "sex tape."

Machado struck back against Trump's insults, saying that he was "aggressive" and "really rude".

Machado, who represented Venezuela in Trump's 1996 "Miss Universe" competition, said the Republican called her "Miss Housekeeping" and "Miss Piggy" when she gained weight after winning the pageant, CNN reported.

At the presidential debate on Monday, Clinton referred to Machado to make a bigger point to Trump about his public treatment of women -- which has become a key campaign issue that hits on his vulnerabilities with both Hispanics and women.

"Donald, she has a name. Her name is Alicia Machado. And she has become a US citizen and you can bet she is going to vote this November," Clinton had said.

Earlier on Tuesday, Trump refused to back down from his criticism of Machado, telling "Fox and Friends" in an interview that she had "gained a massive amount of weight and it was a real problem".

"Not only that, her attitude, and we had a real problem with her, so Hillary went back into the years and she found this girl -- this was many years ago. And found the girl and talked about her like she was Mother Theresa. And it wasn't quite that way but that's OK. Hillary has to do what she has to do."