Republican Donald Trump is vowing to hit rival Democrat Hillary Clinton harder in the next US presidential debate after she put him on the defensive by accusing him of being racist, sexist and a tax dodger during their first matchup.
Ms Clinton blasted Mr Trump again on Tuesday the day after a forceful performance in the first of three scheduled presidential debates ahead of the election.
The New York real estate mogul, she said, "was making charges and claims that were demonstrably untrue, offering opinions that I think a lot of people would find offensive and off-putting".
Mr Trump, making his first run for public office, praised himself for not attacking Ms Clinton about the marital infidelity of her husband, former President Bill Clinton, during the debate at Hofstra University but said in a morning interview with Fox News that he may take up the attack line going forward.
Mr Trump added that when Ms Clinton criticised him for his treatment of women, he resisted.
"I was going to hit her with her husband's women. And I decided I shouldn't do it because her daughter was in the room."
Ms Clinton brushed off Mr Trump's vow, saying, "He can run his campaign however he chooses".
Mr Trump himself had a high-profile affair with Marla Maples, the woman who would be his second wife while he was still married to his first wife, Ivanka Trump. He eventually divorced Maples and married his third and current wife, Melania Trump.
The television audience for debate looks set to approach 80-million viewer record for such events set in 1980, early Nielsen viewership data cited by US media suggested.
Mr Trump sought to deflect criticism of his debate performance, saying the debate moderator, Lester Holt of NBC News, asked him "very unfair questions" and that he was given a "very bad" microphone.
Ms Clinton, speaking to reporters on her campaign plane, said, "Anyone who complains about the microphone is not having a good night".