“I know that it can be very easy, under the intensive pressures of a campaign, for even well-intentioned people to fall into shady tactics —  to rationalize this on the grounds that what is at stake is of such importance to the Nation that the end justifies the means. And both of our great parties have been guilty of such tactics in the past.
In recent years, however, the campaign excesses that have occurred on all sides have provided a sobering demonstration of how far this false doctrine can take us. The lesson is clear: America, in its political campaigns, must not again fall into the trap of letting the end, however great that end is, justify the means.
I urge the leaders of both political parties, I urge citizens, all of you, everywhere, to join in working toward a new set of standards, new rules and procedures to ensure that future elections will be as nearly free of such abuses as they possibly can be made. This is my goal. I ask you to join in making it America's goal.”

1970s, First Watergate Speech (1973)