Spencer's character, vice presidential candidate Leo McGarry, was seen in a flash-forward sequence set three years in the future during the "West Wing" season opener in September, The Hollywood Reporter noted Monday.
Spencer died of a heart attack Friday at age 58.
Ironically, his character suffered a heart attack last season, but quickly recovered.
In the storyline that has been unfolding this season, McGarry was the running mate of Democratic Congressman Matt Santos, played by Jimmy Smits.
A new "West Wing" episode is not scheduled until January and the show's writing staff was scheduled to meet this week to figure out what direction the show will now take, The Reporter said.