How did James Buchanan get the nickname of old buck?

James Buchanan earned the nickname "Old Buck" during his long political career, particularly in the 1850s. The term "Buck" was a slang reference to a young man or a dandy, and it was adopted by Buchanan's supporters as a term of endearment. The nickname also served to highlight his status as a seasoned politician, emphasizing both his age and experience when he ran for president in 1856.