Dixiecrats
President Franklin Roosevelt's electoral body in 1945 had included a diverse, in fact contradictory, set of elements — both conservatives and liberals, northern and southern Democrats and Republicans. By 1948, however, the civil rights issue revealed the real philosophical differences between northern and southern Democrats as never before. The move of Southern states from solidly Democrat to solidly Republican began to take place. In that environment, the Dixiecrats and the “Southern Strategy" was born.
At the 1948 Democratic National Convention, a group led by Senator Hubert Humphrey of Minnesota proposed some controversial new civil rights planks of racial integration and the reversal of Jim Crow laws to be included in the party platform. Southern Democrats were dismayed. President Harry S. Truman was caught in the middle for his recent executive order to racially integrate the armed forces. As a compromise, he proposed the adoption of only those planks that had been in the 1944 platform. That was not enough for the liberals. Truman's own civil rights initiatives had made the civil rights debate unavoidable.
https://www.u-s-history.com/pages/h1751.html
