Donald Trump will not participate in the longstanding tradition of US presidents throwing out a ceremonial first pitch at Washington Opening Day games.
Mr Trump was extended an invitation by the Nationals but declined due to a scheduling conflict, the spokeswoman.
Inviting the President is a tradition over a century old, and both former presidents Barack Obama and George W Bush threw out ceremonial first pitches at Nationals games.
Washington opens its season on Monday against the Miami Marlins.
William Howard Taft was the first president to throw out a ceremonial first pitch for the Washington Senators in 1910. Thirteen presidents in all have thrown out ceremonial first pitches for the Nationals and Senators franchises.