US Republican presidential candidate Donald Trump has intensified his criticism of Hillary Clinton after she said he had a "penchant for sexism," warning his Democratic rival against using the "woman card".
In a familiar pattern for Trump, he responded to fire - this time over a vulgarity he used in describing Clinton's 2008 primary loss - with fire.
"Be careful Hillary as you play the war on women or women being degraded card," Trump said in a Twitter post on Wednesday.
Later he tweeted: "Hillary, when you complain about 'a penchant for sexism,' who are you referring to. I have great respect for women. BE CAREFUL!"
The real estate tycoon, who is the front-runner for the 2016 Republican nomination, drew widespread criticism this week after using Yiddish slang for a man's genitals to describe Barack Obama's victory over Clinton in the 2008 Democratic presidential race, saying: "She got schlonged."
While Clinton's campaign would not comment on Thursday on Trump's warning, she addressed his rhetoric in an interview with the Des Moines Register in Iowa, where she was campaigning for the state's early presidential contest.
"I really deplore the tone of his campaign, the inflammatory rhetoric that he is using to divide people, and his going after groups of people with hateful, incendiary rhetoric," she said on Tuesday, the day after Trump's slang remark.
"It's not the first time he's demonstrated a penchant for sexism."
Clinton said she does not respond to the candidate personally "because he thrives on that kind of exchange".
Trump has been criticised for calling women fat pigs, dogs and slobs and in August his comments about Fox News anchor Megyn Kelly were widely interpreted as referring to her menstrual cycle.
He denied that was his intention.
Whether the topic is women, Muslims or immigrants, Trump has consistently doubled down after making inflammatory statements during the 2016 White House campaign.
Trump's political director, Michael Glassner, told CNN it was ironic for Clinton to talk about Trump's attitude toward women given her husband Bill Clinton's sexual scandal in the White House.
In what may have been his most potent warning, Trump told Fox News on Wednesday: "I really haven't gone after Hillary yet and there's a lot to go after."
