Utah’s Assistant Attorney General Steven Wuthrich sent a tirade of abuse to Salt Lake City councillor Darin Mano after “the interruption to my tranquillity”, he admitted.

According to NBC News, he wrote in an email: “I will do everything in my power to see you never get elected to any office higher than dog catcher.

“I hate you. I hate your family. I hate your solicitors. I hate your contributors. I hate your sponsors.”

Mr Wuthrich signed off: “Kindly die and go to hell motherf*****!!!!”

In a statement apologising for the outburst, the prosecutor said he “was awakened from a nap and reacted with undue anger”.

He added: “Since then I have regretted the ferocity and language of that email. My words were uncivil and unprofessional.”