OKLAHOMA CITY (AP) — A Democratic candidate for U.S. Congress in Oklahoma is apologizing for removing his opponent's yard signs ahead of Tuesday's primary election.

Retired college professor Tom Guild issued a statement Monday saying removing the signs "was a mistake on my part for which I sincerely apologize."

Images of man dressed similarly to Guild bending over near opponent Kendra Horn's signs were posted on social media over the weekend. Guild did not immediately return a telephone message seeking comment.

The 64-year-old Guild is among six Democrats running in Tuesday's election for the 5th Congressional District held by Republican Rep. Steve Russell. Russell is heavily favored to win the GOP nomination. It's been more than 40 years since a Democrat has represented the district.

The incident was first reported by The Oklahoman newspaper.