The official pictured Obama's face on the body of a baby chimpanzee, evoking a stinging public rebuke from the local Republican party chairman, who also demanded an ethics investigation into the incident.
Marilyn Davenport, a 74-year-old elected member of the Orange County Republican Central Committee, sent an apology email yesterday, asking for the nation's forgiveness for what she termed as her "unwise behaviour".
"To my fellow Americans and to everyone else who has seen the email I forwarded and was offended by my action, I humbly apologise and ask for your forgiveness of my unwise behaviour," Davenport said in a statement obtained by CNN.
Davenport, who is a Tea Party activist, said she felt the email was a joke.
The email sent by her on Friday shows an image of a chimpanzee parents and a child, with Obama's face superimposed on the young chimp.
The text beneath the picture read, "Now you know why no birth certificates", an apparent reference to a demand that Obama produce more evidence that he is US born.
The cartoon triggered a rebuke for Davenport from the Californian National Association as well as from the state Republican party that she issue a written apology.
CNN said that the White House did not immediately react to the email.