Leslie Gibson, a US Republican candidate for a state seat in Maine, has apologised after calling Emma González, a survivor of the Florida school shooting and the young face of the anti-gun movement, a “skinhead lesbian”.

In a since-deleted post to Twitter, Mr Gibson wrote there was “nothing about that skin head lesbian that impresses me and there is nothing that she has to say unless you’re a frothing at the mouth moonbat”.

In another tweet, he said Ms González should not be regarded as a survivor of the Florida massacre because she was “in a completely different part of the school”.

He also used the social media account to accuse David Hogg, another Florida survivor and anti-gun activist, of being a “bald-faced liar”.

After intense backlash, the candidate issued an apology on Twitter before deleting his account.

“I would like to extend to you my most sincere apology for how I addressed you. It was wrong and unacceptable,” he wrote.

“You are doing work that is important to you. I would like to extend my hand in friendship and understanding to you.”

Mr Gibson is currently the only declared candidate for Maine’s 57th district, which means he will be elected unopposed to the state’s lower house.

Ms González rose to fame for an emotive speech in front of thousands of people where she “called BS” on Donald Trump and the National Rifle Association for their alleged inaction on gun reform.

Since the speech she has doubled the number of Twitter followers of the NRA gun lobby, as the anti-gun movement gains traction in the US.

The student identifies as bisexual. She has denied her buzzcut hairstyle was about taking a “feminist stand” but rather for practical reasons.

On an Instagram post, she explained: “I decided to cut my hair because it was a pain in the neck … it was expensive to keep it up, and as prom time came around, I figured it would be cheaper to not have to worry about doing my hair.

“The more my parents said no, the more I wanted it. Actually, I even made a Powerpoint in order to convince them that I should do it.”