In a statement, Congresswoman Madeleine Bordallo says she has accepted John Whitt's resignation with immediate effect.
Mr Whitt was arrested in Maryland in April on allegations of second-degree assault and unwanted sexual contact, and charges were filed in a local court this week.
Ms Bordallo says she has a responsibility to represent and advocate the people to the best of her abilities, and the pending allegations against Mr Whitt could detract from carrying out those responsibilities.
She has appointed her legislative director, Matthew Herman, as acting Chief of Staff.
Source:
Radio New Zealand International