In several tweets early Friday, Republican presidential candidate Donald Trump publicly shamed former Miss Universe Alicia Machado, a tirade that prompted Democratic nominee Hillary Clinton to denounce him as "unhinged."

The tweets came after Monday's presidential debate with Clinton, in which past comments when he criticized Machado for gaining weight after she won the crown in 1996 were brought up by Clinton.

"Who gets up at 3 o'clock in the morning to engage in a Twitter attack?" Clinton asked at an event in Coral Springs on Friday, adding that Trump's tweets against Machado showed him to be is "temperamentally unfit" to be president.

Responding in a later tweet, Trump said: "For those few people knocking me for tweeting at three o'clock in the morning, at least you know I will be there, awake, to answer the call!"

Trump had denounced Machado in a television interview the morning after Monday's debate and resumed his attacks with the tweets on Friday, in which he questioned her sexual history and suggested Clinton may have helped her become a citizen. 

'Cheap lies'

In his tweets, Trump made a reference - without giving evidence - to a sex tape involving the Venezuelan-born Machado.

US political website Politico reported that Machado has starred in racy reality TV programs and posed naked for Playboy's Mexican edition, but said media outlets have found no evidence that she has starred in pornographic films.

Machado - now a US citizen - dismissed the fresh attacks as "cheap lies" on Facebook.

"By way of his hate campaign, the Republican candidate insists on discrediting and demoralizing a woman, which is clearly one of his most frightening characteristics," she wrote in Spanish, next to a photo of herself draped in an American flag.

On Friday, Clinton thanked Machado "for all she has done and the courage she has shown," said campaign spokesman Nick Merrill. Speaking to reporters, campaign communications director Jennifer Palmieri said Clinton had not helped Machado become a citizen.

In for a rough ride

Trump has vowed to hit Clinton harder in their next debate on October 9, suggesting he might bring up the infidelities of her husband, former President Bill Clinton.

With less than six weeks to go before the November 8 election, the latest Reuters/Ipsos national tracking poll, released Friday, showed Clinton leading by 43 percent to Trump's 38 percent among likely voters.

Meanwhile, Trump's complaint about his microphone not working properly during the televised presidential debate on Monday was upheld on Friday by the Commission on Presidential Debates. "Regarding the first debate, there were issues regarding Donald Trump's audio that affected the sound level in the debate hall," the commission said on its website, without giving details.

Clinton, clearly enjoying the moment after a debate in which Trump increasingly struggled as the evening wore on, quipped that "anyone complaining about microphones is not having a good night."

jbh/cmk (AP, AFP, Reuters)