William McKinley actually said...
by virtue of the power vested in me by the Constitution and the laws, and deeming sufficient occasion to exist, have thought fit to call forth, and hereby do call forth, volunteers to the aggregate number of 125,000 in order to carry into effect the purpose of the said resolution
Context
Proclamation 412—Calling Forth Volunteers to Serve in the War with Spain
04/22/1898