Police arrested James Byrne, 70, of Madison, in connection with the threat on the Boston Post Road home of Republican Town Committeee Chair Tom Banisch.
At the time of the threat, about 50 guests, including several candidates for statewide office, were inside the Banisch home.
The threat was called into police headquarters around 4:30 p.m. on Sunday. Connecticut State Police Bomb Squad responded to the scene and evacuated the home for about an hour.
Byrne faces several charges, including first-degree threatening and breach of peace. He will face a judge on Sept. 28.