Excerpts of the President's News Conference
I have here a note of inquiry about legislation. It is always rather embarrassing for me to discuss legislation that is pending, about which there is a controversy in the Congress. As I have explained many times, I can't very well announce beforehand that I am going to veto a bill, or that I am going to sign it. I have to keep my mind open about those things until the proposal comes to me. Nobody knows what the bill may contain when it gets here, so that I have to wait and see. I have general policies about legislation which I have announced quite a good many times, and I think you won't make much of any mistake if you look and see what public announcements I have made about my policies, and until I announce otherwise you are probably warranted in supposing that is my attitude and mind.
Source: "The Talkative President: The Off-the-Record Press Conferences of Calvin Coolidge". eds. Howard H. Quint & Robert H. Ferrell. The University Massachusetts Press. 1964.
Calvin Coolidge, Excerpts of the President's News Conference Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/349042