Joseph S Clark Jr
Senator Joseph S. Clark Jr. was Senator from Pennsylvania from 1957 to 1969.
Speech Relevance
In 'A Time For Choosing', Reagan states,
And Senator Clark of Pennsylvania, another articulate spokesman, defines liberalism as "meeting the material needs of the masses through the full power of centralized government." Well, I for one resent it when a representative of the people refers to you and me--the free man and woman of this country—as "the masses." This is a term we haven't applied to ourselves in America. But beyond that, "the full power of centralized government"—this was the very thing the Founding Fathers sought to minimize.
From The Atlantic, we find one quote from Senator Clark (at the time of the quote, Mayor of Philadelphia):
To lay a ghost at the outset and to dismiss semantics, a liberal is here defined as one who believes in utilizing the full force of government for the advancement of social, political, and economic justice at the municipal, state, national, and international levels.... A liberal believes government is a proper tool to use in the development of a society which attempts to carry Christian principles of conduct into practical effect. (Atlantic, July 1953, p. 27)