Fresh off his presidential clash with Hillary Clinton, Donald Trump doubled down Tuesday on criticism of a former Miss Universe he accused of getting too fat, comments that could repel women voters.

Alicia Machado, who won the crown in 1996, has accused Trump -- whose company owned the Miss Universe pageant until last year -- of calling her "Miss Piggy" and "Miss Housekeeping," and publicly humiliating her over her post-victory weight gain.

The morning after Clinton, the Democratic presidential nominee, invoked Machado's experience as an example of how the brash Republican billionaire treats women, he lashed out at the beauty queen.

"She gained a massive amount of weight, and it was a real problem," Trump told Fox News television Tuesday.

"She was the worst we ever had. The worst, the absolute worst," he added. "She was impossible."

During their first presidential debate Monday night, Clinton raised Machado's case in an exchange over Trump's assertion that the Democratic candidate did not "look presidential."

Excoriating Trump for his treatment of women, she recalled that he had called Machado "Miss Piggy," and "Miss Housekeeping" because she is Latina.

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

Trump appeared startled by the accusation.

"Where did you find this?" Trump asked Clinton three times.

Shortly after the debate, Clinton's campaign released a video in which Venezuela-born Machado says she was scared of and intimidated by Trump.

"He'd yell at me all the time. He'd tell me 'You look ugly,' or 'You look fat,'" she says.

"He bears many grudges, and harbors a deep racism, and he is convinced that there are lesser human beings than him."

Trump is seen in 1990s footage saying Machado "weighed 118 pounds or 117 pounds (53 kilograms) and she went up to 160 or 170 (72.5 or 77 kg). So this is somebody that likes to eat."

Throughout his campaign Trump has faced intense scrutiny over his treatment of women, and Clinton assailed her rival on the issue.

"This is a man who has called women pigs, slobs and dogs, and somebody who has said pregnancy is an inconvenience to employers, who has said women don't deserve equal pay unless they do as good a job as men," Clinton said.

Machado, following the debate, tweeted insults in Spanish at Trump, calling him #ratanazi, or "Nazi rat."

During a news conference call Tuesday, speaking in a mix of Spanish and English, the former beauty queen heaped even more contempt on Trump for his past mistreatment.

"He doesn't remember me, he doesn't remember many things that he did to me, or that he told me," Machado told reporters.

"It was evident that maybe he doesn't remember an 18-year-old girl, whom he insulted and offended and mistreated a thousand times. But I'll always remember."

Meanwhile, some of her remarks to reporters -- and others written on her @machadooficial Twitter account -- gushed support for the Democratic nominee.

"She is ready and able to be president," Machado tweeted.

"@HillaryClinton arriba!" ("@Go HillaryClinton!")