“Our country is now taking so steady a course as to show by what road it will pass to destruction, to wit: by consolidation of power first, and then corruption, its necessary consequence. The engine of consolidation will be the Federal judiciary; the two other branches the corrupting and corrupted instruments.”

Source: Lullaby (2002), Chapter 9

Attributed, In the Media
Source: Financial Times http://www.ft.com/intl/cms/s/0/7ba47200-015c-11e6-99cb-83242733f755.html#axzz45lPGQfQg "Transparency thwarts the abuse of power to enrich the powerful", Column in the Financial Times, 13 April 2016.

The Corruptions of Our Time, p. 248
The Corrupt Society - From Ancient Greece To Present-Day America (1975)

Source: General sources, Chapterhouse Dune (1985)
Context: All governments suffer a recurring problem: Power attracts pathological personalities. It is not that power corrupts but that it is magnetic to the corruptible. Such people have a tendency to become drunk on violence, a condition to which they are quickly addicted.

Source: 5 August 2021, Speech after oath taking ceremony in Tehran https://www.tehrantimes.com/news/463741/Raisi-officially-takes-oath-of-office-as-Iran-s-president

Letter http://oll.libertyfund.org/index.php?option=com_content&task=view&id=1407&Itemid=283 to Mandell Creighton (5 April 1887), published in Historical Essays and Studies, by John Emerich Edward Dalberg-Acton (1907), edited by John Neville Figgis and Reginald Vere Laurence, Appendix, p. 504; also in Essays on Freedom and Power (1972)
Paraphrased variant: All power tends to corrupt and absolute power corrupts absolutely.
Context: I cannot accept your canon that we are to judge Pope and King unlike other men, with a favorable presumption that they did no wrong. If there is any presumption it is the other way against holders of power, increasing as the power increases. Historic responsibility has to make up for the want of legal responsibility. Power tends to corrupt and absolute power corrupts absolutely. Great men are almost always bad men, even when they exercise influence and not authority: still more when you superadd the tendency or the certainty of corruption by authority. There is no worse heresy than that the office sanctifies the holder of it. That is the point at which the negation of Catholicism and the negation of Liberalism meet and keep high festival, and the end learns to justify the means.

Nadia Chernyshevski
Green Mars (1993)

Source: The Postman (1985), Section 3, “Cincinnatus”, Chapter 14 (p. 267)
Variant: It is said that power corrupts, but actually it’s more true that power attracts the corruptible. The sane are usually attracted by other things than power.
As quoted in Values of the Wise: Humanity's Highest Aspirations (2004) by Jason Merchey, p. 120
This is very similar to the expression by Frank Herbert in Chapterhouse: Dune (1985): "All governments suffer a recurring problem: Power attracts pathological personalities. It is not that power corrupts but that it is magnetic to the corruptible. Such people have a tendency to become drunk on violence, a condition to which they are quickly addicted."
Context: It’s said that “power corrupts,” but actually it’s more true that power attracts the corruptible. The sane are usually attracted by other things than power. When they do act, they think of it as service, which has limits. The tyrant, though, seeks mastery, for which he is insatiable, implacable.