Context:
The influence of the Executive in controlling the freedom of the elective franchise through the medium of the public officers can be effectually checked by renewing the prohibition published by Mr. Jefferson forbidding their interference in elections further than
giving their own votes, and their own independence secured by an assurance of perfect immunity in exercising
this sacred privilege of freemen under the dictates of their own unbiased judgments. Never with my consent shall an officer of the people, compensated for his services out of their pockets, become the pliant instrument of Executive will.
More:
http://www.presidency.ucsb.edu/ws/index.php?pid=25813