A major US conservative forum has dropped Donald Trump as a speaker, saying it was unacceptable for him to suggest that a journalist was tough on him because she was menstruating.
Mr Trump said Megyn Kelly of Fox News "had blood coming out of her eyes, blood coming out of her wherever".
Ms Kelly challenged him on remarks he made about women during a TV debate.
Conservative group RedState said Mr Trump was implying she was hormonal. Mr Trump later denied this in a tweet.
"Re Megyn Kelly quote: 'you could see there was blood coming out of her eyes, blood coming out of her wherever' (NOSE)," he wrote.
Re Megyn Kelly quote: "you could see there was blood coming out of her eyes, blood coming out of her wherever" (NOSE). Just got on w/thought— Donald J. Trump (@realDonaldTrump) August 8, 2015
A later statement from his campaign said "only a deviant" would think Mr Trump meant anything else.
Mr Trump was one of 10 Republican presidential candidates in a TV debate co-hosted by Ms Kelly this week, which was watched by a record 24 million people.
Early on in the debate, Ms Kelly asked him why voters should elect a man who has called women "fat pigs, dogs, slobs and disgusting animals".
Mr Trump joked that he only said that about TV personality Rosie O'Donnell before adding: "I don't have time for total political correctness."
So many "politically correct" fools in our country. We have to all get back to work and stop wasting time and energy on nonsense!— Donald J. Trump (@realDonaldTrump) August 8, 2015
After the debate, he took to Twitter to say Ms Kelly had "really bombed" and that she hadn't been "very good or professional".
Speaking on CNN, he said Ms Kelly was "a lightweight" and that he "couldn't care less about her", before making the comment about blood.