Offensive graffiti has been sprayed on the window of the office for the Warwick district branch of the Liberal Democrat political party in Leamington.
The incident took place at the office in Clemens Street overnight between yesterday (Tuesday December 17) and this morning (Wednesday December 18).
The graffiti refers to people making protest votes in the recent general election and includes the hashtag #Boris
John Kelly, the branch's vice chairman, said: "The aggressive tone of the recent election campaign encourages this sort of mindless behaviour.
"It is unfortunate that our politics has gone in this direction."