Said during debate she had 'blood coming out of her... wherever' - widely interpreted as a reference to her menstrual cycle

Trump has been under fire for attacking Fox Host over debate questions

Said: 'If you mess with the bull you're going to get the horns, sweetheart'

Tana Goertz, the co-chair of Trump's Iowa campaign, defended her boss

'Fair game': Tana Goertz, a co-chair of Trump's Iowa campaign, defended his attacks on Megyn Kelly

A Donald Trump official leading his political campaign in Iowa has said his attacks on Fox News host Megyn Kelly are 'fair game'.

Tana Goertz, his campaign co-chair in the battleground state, said that she was not offended by Trump's suggestion that Kelly asked him tough questions because there was 'blood coming out of her wherever'.

Goertz instead said the abuse is part of political debate, saying: 'If you mess with the bull you're going to get the horns, sweetheart'.

Trump's comments, made Friday night in a CNN segment where he also called her a 'lightweight' and 'overrated', were widely interpreted as a crude reference to Kelly's menstrual cycle.

He has since claimed he was referring to her nose.

Goertz, whose association with Trump began when she appeared on season three of The Apprentice, told BuzzFeed News that she was 'not offended' by the statement, and does not think it is about her period.

She said: 'You know with Mr Trump, he believes that he responds to men and women with equal intensity so you know Megyn was attacking him at the debate and he just fired back. It’s fair game.'

Meanwhile Trump was roundly criticized for the remarks by other Republican candidates, members of the public, and even his own staff.

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Roger Stone, a longtime associated of Trump, dramatically exited the campaign Saturday.

'Get the horns'? Goertz said that Megyn Kelly, above during the debates, deserved her harsh treatment because she asked Trump difficult questions

He says he abandoned his campaign after failing to persuade him to stop his personal attacks and focus on the issues. Trump says he fired Stone.

The real estate billionaire was forced to divert his campaign Saturday after his invitation to a gathering of conservative activists in Atlanta, Georgia, was rescinded over his attacks on Kelly.

He was slated to appear at the RedState gathering, where Ted Cruz, Jeb Bush, Chris Christie and others made speeches to the GOP faithful.

Associates: Goertz has known Trump since she was a contestant on the third series of The Apprentice

But organizer Eric Erickson made it clear that Trump would not be welcome in light of the comments. In return Trump called him a 'loser' and said he hadn't wanted to go anyway.

During his speech at the event, Jeb Bush weighed in on the row.