The state director for Republican Senator Kelly Ayotte of New Hampshire, David Wihby, was arrested at a hotel during a prostitution sting.
The 62-year-old was charged with one misdemeanour count of soliciting a prostitute. Wihby has stood down following his arrest.
Senator Ayotte released a statement reading: "I am shocked and deeply saddened that David Wihby, my state director and a friend for many years, has been arrested under these circumstances. David obviously cannot continue his duties, and I have accepted his resignation. This is a very difficult time, and my thought and prayers are with everyone involved."
"This is a very difficult time, and my thoughts and prayers are with everyone involved."
Wihby, also serves as the vice chairman of the Manchester, New Hampshire, school board, has not commented on the charges.
Nashua police told News 9 that they arrested 10 men over the last week on charges of prostitution at two hotels. They said the men, who were between the ages of 24 and 64 years old, responded to advertisements from women online.
"There would be a talk about exchange of money for sexual acts and upon having that done where there was an agreement between the two of them, the individual would be placed under arrest," Nashua police Capt. Denis Linehan said.
The suspects allegedly caught in the sting were from New Hampshire and Massachusetts.
He was released on $2,000 bail (£1,343) and is due to be arraigned on 11 May.