“I pledge you, I pledge myself, to a new deal for the American people.”

August 5, 1958, as quoted in Dr Lorenzo Kimball (1972) The Changing of Political Power in Iraq, 1958 to 1971.

1963, Third State of the Union Address
Context: Little more than 100 weeks ago I assumed the office of President of the United States. In seeking the help of the Congress and our countrymen, I pledged no easy answers. I pledged — and asked — only toil and dedication. These the Congress and the people have given in good measure.

Source: Fiction, The Book of the New Sun (1980–1983), The Urth of the New Sun (1987), Chapter 19, "Silence" (p. 132)

2010s, 2016, July, 2016 Republican National Convention (21 July 2016)

The Hoover Policies (1937)

Address Accepting the Democratic Party Nomination for the Presidency of the United States — Memorial Coliseum, Los Angeles (15 July 1960) http://www.jfklibrary.org/Research/Research-Aids/Ready-Reference/JFK-Quotations.aspx<!-- Online by Gerhard Peters and John T. Woolley, The American Presidency Project -->
1960
Context: Their platform, made up of left-over Democratic planks, has the courage of our old convictions. Their pledge is a pledge to the status quo — and today there can be no status quo.

2010s, 2016, July, (21 July 2016)

Speech from the Sixth Nazi Party Congress, Nuremberg; September 8th, 1934 https://web.archive.org/web/20150605015000/http://campbellmgold.com/archive_esoteric/hitler_closing_speech_triumph_of_the_will.pdf.
Video footage of this quotation can be found in the film Triumph of the Will
1930s
Context: It shall always be only a fraction of the people who stand out as truly active fighters, and more is expected from them than from the millions of their fellow countrymen. For them, the mere pledge of "I believe" is not enough, but rather the oath: "I fight!"

Excerpts from inaugural address (February 25, 2013)