Simplify the following text for a Grade 13 native English-speaking person.
Original: The series is set in the West Wing of the White Houseâ '' where the Oval Office and offices of presidential senior staff are locatedâ '' during the fictional Democratic administration of Josiah Bartlet ( played by Martin Sheen ) .
Simplified: The series is set in the West Wing of the White Houseâ '' where the Oval Office and offices of presidential staff are locatedâ '' during the fictional presidency of Josiah Bartlet ( played by Martin Sheen ) .