General Manager Ernie Grunfeld will address the move today.
Wittman's tenure is over after four-plus season and two playoff appearances.
Wizards close season against the Hawks in what may be Coach Randy Wittman's final game.
Wittman said Gerald Henderson should've been called for a five-second violation with 15.8 seconds left and the Trail Blazers trailing by two points.
The Wizards have won four straight games to reach .500 for the first time since Jan. 15.
Saunders died of cancer in October.
Washington coach is on leave for two games following the death of his older brother Saturday.
Don Newman will assume the coaching duties against the Thunder and Warriors.
A loss would sink the Wizards to five games below .500 for the first time this season.
Wittman's older brother Rick died unexpectedly in Indianapolis early Saturday.