Rocked by allegations of sexual assault, Donald Trump on Thursday lashed out at his female accusers as "horrible, horrible liars" as the deeply divisive presidential campaign sank further into charges and countercharges of predatory treatment of women.

The Republican businessman devoted much of a Florida speech to defending himself against multiple reports of inappropriate sexual behavior - accusations that he blamed on Hillary Clinton's campaign and the news media.

"These vicious claims about me, of inappropriate conduct with women, are totally and absolutely false. And the Clintons know it," Trump declared. His accusers, he said, "are horrible people. They're horrible, horrible liars."

The comments came minutes after he called a reporter "a sleazebag" for asking whether Trump had ever touched or groped a woman without her consent.

First lady Michelle Obama, meanwhile, offered an emotional counterargument in the battleground state of New Hampshire, warning that Trump's behavior sends a dangerous message to the nation's children.

"The belief that you can do anything you want to a woman, it is cruel, it is frightening, and the truth is it hurts," Obama said. She added, "We can't expose our children to this any longer, not for another minute, let alone for four years."

The New York Times and the Palm Beach Post on Wednesday reported stories about three women who alleged Trump had inappropriately touched them. Separately, a People Magazine reporter wrote a detailed first-person account of being attacked by Trump while interviewing the businessman and his wife, Melania Trump.

Trump said the claims "are all fabricated."

"They're pure fiction, and they're outright lies. These events never happened," he said at the West Palm Beach rally.

He added, "I will not allow the Clinton machine to turn our campaign into a discussion of their slanders and lies."

Rather than trying to make up ground by shifting attention back to issues like trade that have energized Trump backers and could appeal to new voters, the Republican campaign appears to be moving swiftly to make Bill Clinton's past a centerpiece of its campaign.

Building on Trump's decision to bring three Bill Clinton accusers to last week's presidential debate, the Republican nominee is expected to have the women appear with him on stage at rallies and do television interviews, according to a person briefed on the plan but not authorized to discuss it publicly. They were not on stage in West Palm Beach.

The Trump campaign's hope is to showcase the decades-old accusations to young voters, particularly women, who may not have been old enough to remember the controversies that dogged the Clintons in the 1990s. If the campaign can't get them to vote for Trump, the hope is that they will stay home and depress turnout, which would likely hurt Democrats.

Hillary Clinton, who is on pace to become America's first female president if her lead holds, has tried to stay above the fray. She has yet to respond directly to Trump's decision to resurrect accusations about her husband.

Meanwhile, emails made public on Thursday show that Hillary Clinton's campaign tried to move the Illinois presidential primary to a later date, saying a contest held after the Super Tuesday primaries might stop momentum for a moderate Republican candidate and emphasizing that Clinton and her husband "won't forget" a political favor.

A November 2014 email hacked from the accounts of Clinton campaign chairman John Podesta was among nearly 2,000 new emails published by WikiLeaks.

"The Clintons won't forget what their friends have done for them," he added. Clinton and her husband, former President Bill Clinton, famously gave special attention to allies considered "friends of Bill."

Clinton's campaign has said the FBI was investigating who hacked Podesta's email.