Who has the power to change the local date/time of Washington D.C., and what is the extent of this power?
Could this power be abused to extend/reduce the terms of elected officials?
Certainly the local time of Washington D.C. can be changed (e.g., time zones or daylight savings).
It is even conceivable that the local date of Washington D.C. could be changed (e.g., if the U.S. decided to hop over the international date line like Kiribati did).
So someone must have the power to change the local date/time of Washington D.C. The Standard Time Act of 1918 and the Uniform Time Act of 1966 suggest that the Congress & President have (a) the power to change local time and (b) the power to limit the power of states to change local time.
(related: In which timezone's "noon" does the US presidency turn over?)