The word "Nazis" was spray-painted on the back wall of the GOP headquarters in Concord, New Hampshire.
The person or people responsible also threw a rock at a back window, leaving glass scattered on the ground below.
After seeing photos of the vandals' work, people who spoke to NBC Boston said it's a reflection of the growing political and racial tensions being felt across the country.
"Awful. It's awful," said Deborah Jakubowski. "It shouldn't be this way, and it really is. It's very bad."
"That's not the way you deal with differences, not in a democracy," said Bob Swartz. "I have real concerns for where we're going."
Concord Police responded to the GOP headquarters just after nine Thursday morning after a staffer found the vandalism.
A broken window and the word "Nazis" spray-painted inside a heart on the side of the building was found around 8:30 a.m.
"These are the type of things that can be a lightening rod for extreme behavior," said Lt. Sean Ford of the Concord Police Department.
According to Patrick Hynes, the GOP spokesman, there was no indication anyone was targeting headquarters.
People said the president should tone down the rhetoric.
"Donald Trump has enabled people to express their disgusting views and hatred and in this case on both sides," said Dennis Jakubowski. "Nobody should write that anywhere, Republican or Democratic."
"I hate to see the Republican Party branded that, but when the leader of your party refuses to make statements I think he needs to make, people overreact," said Swartz.
The graffiti has been removed from the building.
Witnesses are asked to call Concord Police with any information that may help find who's responsible.