Donald Trump has become the target of a Twitter campaign by women angry at his sexist remarks after the Republican candidate's debate last week.
After the debate, Trump seemed to suggest Fox News host Megyn Kelly had questioned him aggressively because she was having her period.
He told CNN's Don Lemon: "You could see there was blood coming out of her eyes, blood coming out of her ... wherever." His attempt at defending himself only made things worse.
Read more:
• Donald Trump says Megyn Kelly's tough questioning was due to menstruation
• Donald Trump's history of flippant misogyny becomes part of his brand
His comments sparked widespread outrage, and inspired Twitter users to come up with the hashtag #periodsarenotaninsult.
Trump's Twitter account has been bombarded with messages from women about all aspects of their menstrual cycle ever since.
But Trump has extended his lead in the race for the Republican presidential nomination despite his chaotic debate performance and the Kelly row, as closest rival Jeb Bush lost ground.
Support for the billionaire held firm at 24 per cent, according to a Reuters/Ipsos poll released yesterday, unchanged since last week's television debate.
His closest rival, former Florida Governor Bush, dropped from 17 points before the debate to just 12 after, according to the online poll.
No other candidate earned more than 8 per cent in the survey, which was conducted between the end of the debate on Friday and Monday.
Other polls seem to confirm that Trump's feud with the media and fellow candidates had done nothing to damage his appeal among Republican voters.
Trump's invitation to a gathering of conservative activists in Georgia was rescinded after his comment about Kelly.