All of these are from Mark Twain, the first person I thought to run through Google:
The political and commercial morals of the United States are not merely food for laughter, they are an entire banquet.
To lodge all power in one party and keep it there is to insure bad government and the sure and gradual deterioration of the public morals.

An honest man in politics shines more there than he would elsewhere.

The new political gospel: public office is private graft.

...when you are in politics you are in a wasp's nest with a short shirt-tail, as the saying is. (Someone explain to me what this means - they will sting you on the ass?)

In religion and politics people's beliefs and convictions are in almost every case gotten at second-hand, and without examination, from authorities who have not themselves examined the questions at issue but have taken them at second-hand from other non-examiners, whose opinions about them were not worth a brass farthing.