"While Donald continues day 5 of his Machado meltdown, we'll be in Florida talking about national service. You'll want to watch."

Republican presidential candidate Donald Trump deepened his attacks on a former beauty queen Alicia Machado on Friday (September 30), alleging the existence of a sex tape as he refused to back away from an issue that threatens to damage his already weak standing among women and Hispanics.

Trump's Democratic rival, Hillary Clinton, raised Trump's treatment of the Venezuelan-born former Miss Universe as an example of how he views women during the two candidates' first debate on Monday night. Clinton said Trump, the former owner of the Miss Universe pageants, had called Machado "Miss Piggy" and also "Miss Housekeeping" because she was a Latina.

Trump did not apologize then and in a television interview the following day he strongly criticized Machado for having gained weight after she won the Miss Universe title in 1996.

With less than six weeks to go until the Nov. 8 election, Trump has refused to let the issue fade and he went on a pre-dawn tirade on Twitter on Friday.

"Did Crooked Hillary help disgusting (check out sex tape and past) Alicia M become a U.S. citizen so she could use her in the debate?" Trump said in a tweet.

He said the Clinton campaign was unaware of the beauty queen's past and was "duped" by her, but offered no proof of his claim. His attack came as he struggled to rebound from what was widely viewed as a loss to Clinton in Monday's (September 26) debate.

Clinton responded to Trump's tweet by calling him "unhinged" and asking "What kind of man stays up all night to smear a woman with lies and conspiracy theories?"

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

Clinton, a former U.S. senator and secretary of state, is the first woman to win the presidential nomination of a major U.S. political party.

Trump's remarks on Friday could hurt him further with women and Hispanic voters, both groups that favor Clinton in opinion polls.

An average of opinion polls aggregated by RealClearPolitics showed Clinton ahead of Trump by 2.9 percentage points on Friday, or 47.3 points to 44.4, slightly lower than the previous margin of 3 points on Wednesday, but well up from 0.9 point on Sept. 19. The latest Reuters/Ipsos national tracking poll, released on Wednesday, showed Clinton leading by 42 percent to Trump's 38 percent among likely voters.