The Wikipedia page on the
American Anti-Imperialist League mentions the brief existence of the National Party in 1900, a party which espoused anti-imperialist and classical liberal policies and was made up mostly of Bourbon Democrats opposed to Bryan. Its presidential candidate, Louisiana Senator Donelson Caffery, apparently dropped out before the election. A brief Google search reveals this
NYT page (PDF) which says the party decided not to replace Caffery but nevertheless decided to mantain one elector in the ballot. Is there any more information on this parties' policies, how long it lasted, and why Caffery dropped out?