“It is worse than a crime, it is a mistake.”

Misattributed

Actually a statement by Joseph Brodsky, as quoted in The Balancing Act : Mastering the Competing Demands of Leadership (1996) by Kerry Patterson, p. 437.
However, compare to the similar Bradbury quotes from 1993 (Seattle Times) and 2000 (Peoria Journal) above.
Misattributed

Source: The Best of Me

Conditions of Progress in Democratic Government (1909).
Context: No greater mistake can be made than to think that our institutions are fixed or may not be changed for the worse. … Increasing prosperity tends to breed indifference and to corrupt moral soundness. Glaring inequalities in condition create discontent and strain the democratic relation. The vicious are the willing, and the ignorant are unconscious instruments of political artifice. Selfishness and demagoguery take advantage of liberty. The selfish hand constantly seeks to control government, and every increase of governmental power, even to meet just needs, furnishes opportunity for abuse and stimulates the effort to bend it to improper uses... The peril of this Nation is not in any foreign foe! We, the people, are its power, its peril, and its hope!

The Idiot (1868–9)

Source: Role Models

1870s, Sixth State of the Union Address (1874)
Context: Enjoined by the Constitution 'to take care that the laws be faithfully executed', and convinced by undoubted evidence that violations of said act had been committed and that a widespread and flagrant disregard of it was contemplated, the proper officers were instructed to prosecute the offenders, and troops were stationed at convenient points to aid these officers, if necessary, in the performance of their official duties. Complaints are made of this interference by Federal authority; but if said amendment and act do not provide for such interference under the circumstances as above stated, then they are without meaning, force, or effect, and the whole scheme of colored enfranchisement is worse than mockery and little better than a crime. Possibly Congress may find it due to truth and justice to ascertain, by means of a committee, whether the alleged wrongs to colored citizens for political purposes are real or the reports thereof were manufactured for the occasion.