He was elected to a second term in 1944, effectively unopposed. When Stevenson left the governorship in January 1947, he was the longest-serving governor in the history of Texas and had presided over a broad and deep economic recovery during the years of World War II. In 1948, Stevenson was a candidate the U.S. Senate in a special election. He led the Democratic primary with 39.7% to 33.7% against Congressman Lyndon B. Johnson of Austin. A third candidate was George Peddy of Houston, originally from Shelby County in East Texas, who had been a write-in candidate for the Senate in 1922 but was defeated by Democratic nominee Earle Bradford Mayfield. With the top two finishers advancing to a runoff election, Peddy and several minor candidates were eliminated from contention. In the hotly contested runoff between Stevenson and Johnson, Johnson won by only 87 votes out of 988,295 cast – one of the closest results in a senatorial election in U.S. history. (As there was only a weak Republican Party in Texas at the time, winning the Democratic primary was tantamount to election.) Stevenson challenged the result on the grounds of ballot stuffing alleged to have occurred in a single precinct, which involved 203 disputed votes from Jim Wells County. The Democratic State Central Committee sustained Johnson's apparent victory by a 29–28 vote. Stevenson was granted an injunction by the federal district court, which barred Johnson from the general election ballot. However, Supreme Court Associate Justice Hugo Black, sitting as a circuit justice, ruled that the federal district court lacked jurisdiction, and that the question was for the Central Committee to decide. He ordered the injunction stayed, and his ruling was upheld by the Supreme Court. After the loss to Johnson, Stevenson retired to Junction. Disenchanted with the Democratic Party, he supported Republican Jack Porter against Johnson in the general election and continued to support Republicans for the rest of his life, including John G. Tower for the Senate and Richard M. Nixon and Barry Goldwater for the presidency. In 1964, Stevenson met at his ranch with the Republican gubernatorial nominee Jack Crichton of Dallas. He did not specifically endorse Crichton over John B. Connally, who had worked for Johnson against Stevenson in the disputed 1948 Democratic primary, but meeting with Crichton was seen as a sign of Stevenson's support. On December 24, 1912, Stevenson married Fay Wright. The couple had one son, Coke Stevenson Jr. Fay died on January 3, 1942. On January 16, 1954, Stevenson married Marguerite King Heap.