This article highly notable figures in U.S. and Canadian national politics who were, or have been alleged by some to be, members of the Ku Klux Klan prior to their public careers. No one serving as a federal judge or senior official in the 1920s is known to have belonged to the second KKK in that period.

Individual cases
A former Klansman to rise to national prominence was the Democratic Senator and later Supreme Court Justice Hugo Black who, early in his political career, defended one of the group's members charged with the assassination of Father James Coyle, an Alabama Catholic priest. Black obtained a "not guilty" verdict from a Klan-controlled jury. Later Black repudiated the Klan and championed a conflicting conception of civil rights.

Hugo Black
In 1924, Harry Truman was a judge in Jackson County, Missouri, which includes Kansas City. Truman was up for reelection, and his friends Edgar Hinde and Spencer Salisbury advised him to join the Klan. The Klan was politically powerful in Jackson County, and two of Truman's opponents in the Democratic primary had Klan support. Truman refused at first, but paid the Klan's $10 membership fee, and a meeting with a Klan officer was arranged. It is also possible to interpret it as a young politician's opportunistic attempt to get ahead. The incident was clearly entwined with the intricacies of machine politics, and may also be seen as an indication of Truman's long evolution in his outlook on race relations.

Robert Byrd
It has been alleged that United States President Warren G. Harding was inducted into the Ku Klux Klan during his administration. The evidence is highly disputed.

Warren Harding
Wyn Craig Wade states Harding's membership as fact and gives a detailed account of a secret swearing-in ceremony in the White House, but bases this claim on a private communication in 1985 from journalist Stetson Kennedy. Kennedy, in turn had, along with Elizabeth Gardner, tape recorded the "late 1940s" deathbed confession of former Imperial Klokard Alton Young, who claimed to have been a member of the "Presidential Induction Team" as Young was dying in a New Jersey Hospital. Young also claimed to have repudiated racism on his deathbed.
Simmons' ultimate vindication came when President Warren G. Harding agreed to be sworn in as a member of the Ku Klux Klan. A five-man "Imperial induction team," headed by Simmons, conducted the ceremony in the Green Room of the White House. Members of the team were so nervous that they forgot their Bible in the car, so Harding had to send for the White House Bible. In consideration of his status, Harding was permitted to rest his elbow on the desk, as he knelt on the floor during the long oath taking. Afterward, the President appreciatively gave members of the team War Department license tags that allowed them to run red lights all across the nation.
Wade also states that "This matter was a major issue in letters sent to Coolidge during the 1924 election", and gives a reference to "Case File 28, Calvin Coolidge papers, Manuscript Division, Library of Congress." In this file there is a letter from Wizard Edward Young Clarke to President Calvin Coolidge on 27 December 1923, charging Wizard Hiram W. Evens with trying to turn the Klan into a "cheap political machine". "It [the Klan] was to be an organization designed to up-build and develop spirituality, morality, and physically the Protestant white man of America."

Evidence for Harding's membership
In their book Freakonomics, economist Stephen J. Dubner and journalist Steven D. Levitt write of their visit to Stetson Kennedy's Florida home, and Harding's possible affiliation with the Klan. However, in a 8 January 2006 article for the New York Times Magazine, Dubner and Levitt wrote an expose of Stetson Kennedy, ("Hoodwinked" pp 26-28) claiming that Kennedy had long systematically exaggerated and misrepresented his work and "hoodwinked" his readers for over 50 years. While nothing in the article specifically dealt with the claim that Harding and the Klan were affiliated with one and other, the implication was that Kennedy's claims and conclusions should be reviewed for accuracy, rather than being accepted at full face value.
Primary source material on file at the Ohio Historical Society in Columbus — which holds more than linear feet of Harding papers from his Presidency does not contain evidence of Harding's alleged membership in the Klan.
Primary source material on file at the Marion County (Ohio) Historical Society (Warren G. Harding Collection) also does not confirm or indicate any involvement in the Klan, nor support the idea of Harding's alleged Klan membership.
Harding was the first American President to publicly denounce lynching and did so in a landmark 21 October 1921 speech in Birmingham, Alabama, which was covered in the national press. Harding also vigorously supported an anti-lynching bill in Congress during his term in the White House. While the bill was defeated in the Senate, such activities would be in direct conflict with Klan membership.
The Site Administrator of the Harding Home Museum (Ohio Historical Society property) in Marion, Ohio, draws a relationship between Harding's alleged Klan activities directly to the rumor-mill stirred up after the President died in 1923 and Mrs. Harding in 1924. (Such rumors also alluded to the President's knowledge of the Teapot Dome scandal, which involved Albert Fall, but not the President.)
Furthermore, Harding's ability to join the Klan is dubious given the numerous rumors that swirled around his supposed mixed race heritage. This theory, promoted by William Estabrook Chancellor, a one-time history professor at the College of Wooster and noted racist, was a direct attempt to keep Harding from securing the Presidency. If true and tested, Chancellor's book, published shortly before the 1920 Presidential election, would have been proof positive that Harding violated the Klan's "one drop rule" which qualified people as being "colored" if they had one drop of Negro blood in their veins.
In his book, The Strange Deaths of President Harding, historian Robert Ferrell Ph.D. claims to have been unable to find any records of any such "ceremony" in which Harding was brought into the Klan in the White House. Also, John Dean, in his 2004 book Warren Harding (edited by Arthur M. Schlesinger), also could find no proof of Klan membership or activity on the part of the 29th President to indicate support of the Klan.
Review of the personal records of Harding's Personal White House Secretary, George Christian Jr., also do not support the contention that Harding received members of the Klan while in office. Appointment books maintained in the White House, detailing President Harding's daily schedules, do not show any such event (but document the visit by members of the Masonic Rite).
In addition to the above points, the 1920 Republican Party platform, which essentially expressed Harding's political philosophy, outright calls for Congress to pass laws combatting lynching.
Anthony also details Harding's induction into the Tall Cedars of Lebanon, a Shrine organization, during the convention week (making note of the conical hat used by the Tall Cedars in the ceremony); Anthony writes that he feels that the charges made by Grand Wizard Alton Young (reported by Wyn Craig Wade in 1985) against Harding were in "retaliation for the Shrine speech and another anti-bigotry speech made by Harding at the dedication of the Alexander Hamilton statue at the Treasury Building" in the previous month of May 1923.
In 2005, The Straight Dope presented a summary [16] of many of these arguments against Harding's membership and added speculation about Harding's motives as further evidence that he would not have joined (i.e. that it while it might have been politically expedient for him to join the KKK in public to do it in private made no sense).

Evidence against Harding's membership or support of the KKK
Wyn Craig Wade has asserted that Edward D. White, the chief justice of the U.S. Supreme Court from 1910 to 1921, told Thomas Dixon "I was a member of the Klan" at the 1915 White House screening of The Birth of a Nation. No evidence has been found that corroborates his alleged admission. White, in any event, never joined the second KKK. He did, however, fight in the Confederate Army during the American Civil War.

Others

^  Wade, 1987.
^  "Woody Guthrie: Natural born anti-fascist" by Kennedy, retrieved 9 September 2005.
^  Wade, 1987, pp. 165, 477.
^  Republican Party Platform of 1920 (available from the American Presidency Project of the University of California, Santa Barbara).
^  Anthony, pp. 412-413.
^  McCullough, p. 164.
^  Steinberg, 1962. Salisbury was a war buddy and former business partner of Truman's. Salisbury states that Truman attempted "to give Jim Pendergast control of [their] business." Salisbury began attacking Truman's patrons, the Pendergast machine, for corruption, and Truman retaliated by telegramming the Federal Home Loan Bank system about Salisbury, leading to Salisbury's conviction for filing a false affidavit. Salisbury contradicts Hinde's statement that the meeting at the Hotel Baltimore was one-on-one, naming at least six individuals who were present. Salisbury states that at the meeting, Truman had to receive a special dispensation to join, because his grandfather Solomon had been a Jew; however, Solomon was not a Jew, and the rumor of Truman's Jewish ancestry was only spread later, by the Klan, once the political lines had been drawn so that Truman was the Klan's enemy.
^  Wade, 1987, p. 196, gives essentially this version of the events, but implies that the meeting was a regular Klan meeting, rather than an individual meeting between Truman and a Klan organizer. An interview with Hinde at the Truman Library's web site ("Oral History Interview with Edgar G. Hinde" by James R. Fuchs, 15 March 1962, retrieved June 26, 2005) portrays it as a one-on-one meeting at the Hotel Baltimore with a Klan organizer named Jones. Truman's biography, written by his daughter (Truman, 1973), agrees with Hinde's version, but does not mention the $10 initiation fee; the same biography reproduces a telegram from O.L. Chrisman stating that reporters from the Hearst papers had questioned him about Truman's past with the Klan, and that he had seen Truman at a Klan meeting, but that "if he ever became a member of the Klan I did not know it."
^  McCullough, 1992.
^  Truman, 1973.
^  Truman, 1973; McCullough, 1992, p. 170.
^  Hamby, 1995.
^  McCullough notes this extensively in his Pulitzer Prize-winning biography of Truman. While Truman had been raised in a family with Southern and Confederate leanings, he still said that he believed "in the brotherhood of all men before the law" (McCullough, p. 247). His work on civil rights was politically damaging but extensive nonetheless.
^  "A Senator's Shame" by Eric Pianin in the Washington Post, 19 June 2005
^  NAACP Civil Rights Federal Legislative Report Card: 108th Congress
^  CNN: "Top Senate Democrat apologizes for slur"
^  Wade, 1987. Cited in Bombingham by Mark Gado, Chapter 2: "The Klan"