change horses in midstream

change horses in midstream and change horses in the middle of the stream

Fig. to make major changes in an activity that has already begun; to choose someone or something else after it is too late. (Alludes to someone trying to move from one horse to another while crossing a stream.) I'm already baking a cherry pie. I can't bake an apple pie. It's too late to change horses in the middle of the stream. The house is half-built. It's too late to hire a different architect. You can't change horses in midstream. Jane: I've written a rough draft of my research paper, but the topic doesn't interest me as much as I thought. Maybe I ought to pick a different one. Jill: Don't change horses in midstream.

See also: change, horse