An employee who works on an irregular or occasional basis or is a special Government employee as defined in 18 U.S.C. 202(a) is subject to the provisions of the applicable subpart of this part when he or she is on duty.
Example: An employee appointed to a special commission or task force who does not have a regular tour of duty may run as a partisan political candidate, but may actively campaign only when he or she is not on duty.
5 C.F.R. §734.601