1966 United States Senate Elections (Four Years of Huckleberry Capone)

The 1966 United States Senate elections were elections on November 8, 1966 for the United States Senate which occurred midway through the second (and only full) term of President Lyndon B. Johnson. With divisions in the Democratic base over the Vietnam War, the unpopularity of President Johnson, with the traditional mid-term advantage of the party not holding the presidency, the Republicans took six Democratic seats. With Republican gains, the balance was now 55-45 in favor of Democrats.

Republican gains included Paul Fannin in Arizona, Edwin H. May Jr. in Connecticut, Charles Percy in Illinois, Tim Babcock in Montana, Harrison Thyng in New Hampshire, Mark Hatfield in Oregon, future Vice President and later President Howard Baker in Tennessee, and a major upset victory by Marshall Parker in South Carolina.