Calvin Coolidge actually said...

I do hereby admonish all citizens of the United States and every person to abstain from every violation of the provisions of the Joint Resol...

I do hereby warn them that all violations of such provisions will be rigorously prosecuted

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.