Complex sentence: Following Obama's election in 2008, Mosteller joined the President-Elect in moving to Washington, D.C., and currently serves as Special Assistant to the President and Director of Oval Office Operations and is one of the longest serving staff members in the administration.
Split into simpler sentences: Following Obama's election in 2008, Mosteller joined the President-Elect in moving to Washington, D.C., and currently serves as Special Assistant to the President and Director of Oval Office Operations. Mosteller is one of the longest serving staff members in the administration.