Strom Thurmond served in the United States Senate from 1954 to 2003 (interrupted in 1956). He was a supporter of the presidencies of Richard Nixon, Gerald Ford, Ronald Reagan, George H. W. Bush, and George W. Bush. First and second terms (1954–1956, 1956–1961)

The incumbent U.S. senator from South Carolina, Burnet R. Maybank, was unopposed for re-election in 1954, but he died two months before the election. Various leaders requested a primary election for choosing the new nominee; however, the Democratic Party selected Edgar A. Brown, a state senator, as the party nominee to replace Maybank without conducting a primary election. Thurmond organized a write-in campaign for the vacant senate seat. He pledged that if he won, he would resign in 1956 to force a primary election. He won the 1954 election easily, receiving almost 63% of the vote. His victory made him the first person to be elected to the U.S. Senate as a write-in candidate. In January 1955, he stated that federal encroachment on states' rights was among the biggest threats to American life and violated the Constitution. He spoke of the importance of education, saying, "it should be a primary duty of the states just as national defense is a primary obligation of the federal government." In July 1955, Thurmond supported the Eisenhower Administration bill for an expanded military reserve law, including peacetime officers receiving compulsory training. He argued the bill would strengthen Eisenhower during the Geneva Summit. He opposed the alternate plan proposed by Senator Richard Russell, which argued to abolish compulsory training in addition to adding a bonus of $400 () to males forgoing active duty. Thurmond asserted that patriotism could not be purchased.

Thurmond co-wrote the first version of the Southern Manifesto, stating disagreement with the 1954 U.S. Supreme Court ruling in Brown v. Board of Education, that desegregated public schools. He was part of the group of Southern senators who shared a commonality of being dispirited with Brown v. Board of Education. In early 1956, he resigned from the Senate, keeping the promise he made two years earlier. He won the primary as well as the general election unopposed. Thereafter, he returned to the Senate in November 1956. In 1957, the Eisenhower administration introduced an amended version of the Civil Rights Bill, imposing expansion of federal supervision of integration in Southern states. In an unsuccessful attempt to prevent the bill passage, Thurmond filibustered the bill, speaking for a total of 24 hours and 18 minutes, the longest filibuster ever conducted by a single senator at the time. Other Southern senators, who had agreed as part of a compromise not to filibuster this bill, were upset with Thurmond because they thought his defiance made them look incompetent to their constituents. Despite his efforts, the Congress passed the Civil Rights Act of 1957 on August 29. In January 1959, the Senate held a debate over changing the rules to curb filibusters, Thurmond expressed the view that the Senate return to the rule prior to 1917, when there were no regulations on the time for debate.

Further attempts at obstruction In February 1960, Thurmond requested a quorum call that would produce at least half the membership of the Senate, the call being seen as one of the delay tactics employed by Southerners during the meeting. 51 senators assembled, allowing for the Senate to adjourn in spite of Thurmond's calls for another quorum call. Thurmond afterward denied his responsibility in convening the Saturday session, attributing it to Democrat Lyndon B. Johnson and opining that those insistent on passing a civil rights bill should be around during discussions on the matter. During his filibuster, Thurmond relied on the book The Case for the South, written by W. D. Workman Jr. Thurmond had known the author for fifteen years as Workman had covered both Thurmond's tenure as South Carolina governor and his presidential campaign, in addition to having served in the military unit Thurmond had organized in Columbia, and having turned down an offer by Thurmond to serve as his Washington office press secretary. The Case for the South, described in 2013 by Loyola history professor and author Elizabeth Shermer as "a compendium of segregationist arguments that hit all the high points of regional apologia", was sent by Thurmond to each of his Senate colleagues and then-vice president Richard Nixon.

Third term (1961–1967)

1960 presidential election On account of Kennedy known support for Civil Rights, Thurmond refused to support the Democratic Party's nominee in the 1960 United States presidential election. Thurmond himself was up for re-election that year and despite his party disloyalty, he won the South Carolina Democratic Primary with nearly 90% of the vote. Like much of the South during this time period, South Carolina was still effectively a one-party state where winning the Democratic primary was tantamount to victory. In the 1960 South Carolina Senate race, Thurmond ran unopposed in the General Election, a Republican candidate did not even appear on the ballot. As of 2021, 1960 remains the last time a Democrat won South Carolina's Class 2 Senate Seat. In the presidential election, he received 14 electoral votes for the vice president (as Harry Byrd Sr.'s running mate). Though Both Byrd and Thurmond had long since moved on from the States Rights' Democratic Party, they were the decided protest ticket of several southern delegates and unpledged electors, who refused to give their support to Kennedy. Though their actual level of electoral support is difficult to determine, "the ByrdThurmond ticket" or "Unpledged candidate", won a plurality of the vote of the vote in Mississippi, finished second (ahead of Nixon) in Alabama and third in Louisiana with 20% of the vote.

Following Kennedy's victory, Thurmond loudly voiced the view that he would be expelled from the Senate Democratic Caucus in retaliation. Though not a position ever endorsed by either Kennedy or the DNC, some Democrats were angered by Thurmond's determined opposition and felt he should be kicked out of the party for his disloyalty.

Kennedy administration

The 87th Congress began without a move to remove Thurmond from the Senate Democratic Caucus, in spite of Thurmond's predictions to the contrary. An aide for Senator Joseph S. Clark Jr. said there was never an intention to pursue recourse against Thurmond, though in his opinion Thurmond should no longer be a member of the party. In February 1961, Thurmond stated his support for imposing quotas per country and category on textile imports; noting that the same practice was being imposed by other countries. He added that American industry would be destroyed by government subsidies that would convert the textile industry to other fields. He later opposed legislation that "would give the president unprecedented authority to lower or wipe out tariff wall [and] would provide for the first time broad government relief to industries and workers", the only Democrat to do so. In December 1961, he addressed the Arkansas American Legion conference in Little Rock. He claimed he had been told that the State Department was preparing "a paper for the turning over of our nuclear weapons to the United Nations." In September 1962, Thurmond called for an invasion of Cuba. In a February Thurmond stated that "the brush curtain around Cuba is a formidable Soviet strategic military base" and estimated between 30,000 and 40,000 Cuban troops were under the leadership of a Soviet general. Hours after the statement was made public, a Pentagon official disputed his claims as being "at wide variance with carefully evaluated data collected by U.S. intelligence" and called for Thurmond to release his proof to the Defense Department. During Paul Nitze's nomination hearing for Secretary of the Navy, Thurmond was noted for asking "rapid fire questions" on military action and focusing on Nitze's participation as a moderator in the 1958 National Council of Churches conference. Along with Arizona Senator Barry Goldwater, Thurmond delayed the Nitze nomination. In spite of Thurmond voting against him, the nomination was approved.

When the Senate debated Kennedy's public school aid bill, Thurmond proposed an amendment prohibiting the government from barring segregated schools from receiving loans or grants. After Kennedy sent Congress his civil rights bill, Thurmond's opposition was clear and immediate. Later that month, Thurmond accused radio and television networks of supporting the views espoused by the NAACP, sparking a dispute with Rhode Island Senator John Pastore. In the weeks leading up to the March on Washington, Thurmond delivered a Senate floor speech, accusing the march's organizer Bayard Rustin of "being a communist, a draft dodger and a homosexual." Rustin biographer John D'Emilio said these remarks unintentionally gave Rustin further credit in the Civil Rights Movement: "Because no one could appear to be on the side of Strom Thurmond, he created, unwittingly, an opportunity for Rustin's sexuality to stop being an issue." Rustin denied Thurmond's charges on August 15.

Investigation into political censorship by the military In August, Thurmond formally requested the Senate Armed Services Committee to vote on whether to vote for "a conspiracy to muzzle military anti-Communist drives." The appearance prompted the cancellation of another public appearance in Fort Jackson, as Thurmond favored marking his proposal with his presence, and his request for a $75,000 committee study was slated for consideration. In November, Thurmond went on a five-day tour of California. At a news conference, he stated that President Kennedy had lost support in the South due to the formation of the National Relations Boards, what he called Kennedy's softness on communism, and an increase in military men being muzzled for speaking out against communism. Thurmond held resentment toward NBC for its lack of coverage of his military muzzling claims. In January 1962, Thurmond charged the military speeches' censorship with having proven State Department officials sold U.S. leadership on the country not wanting to win the Cold War. That month, Senate investigators into the military censoring disclosed having obtained documents not given to them by Secretary of Defense Robert McNamara. Thurmond stated the evidence was obtained through checking with the individuals censoring, describing them as just taking orders. He added that the issue of censoring had predated the Kennedy administration, though charged the incumbent executive branch with having increased its practice. The committee was ended on June 8. In May, Thurmond was part of a group of Senate orators headed by John C. Stennis who expressed opposition to the Kennedy administration's literacy test bill, arguing that the measure was in violation of states' rights as defined by the Constitution. After the Supreme Court ruled state composed prayer in public schools was unconstitutional, Thurmond urged Congress to take steps to prevent the Court from making similar decisions.

Johnson administration