Final answer:
President Harry Truman's civil rights initiatives faced opposition from Dixiecrats within the Democratic Party and the KKK, impacting his ability to fully implement his civil rights policies.
Step-by-step explanation:
The forces that obstructed President Harry Truman's civil rights initiatives were primarily within his own party, the Democratic Party. The factions that opposed civil rights, known as Dixiecrats, formed the States' Rights Democratic Party to push back against Truman’s initiatives. Additionally, groups outside of the political sphere, like the Ku Klux Klan (KKK) and other white segregationists, were part of the social resistance to civil rights advancements during Truman's presidency.
Truman faced opposition from the southern delegates of his party, who broke away and formed the States' Rights Democratic Party, commonly referred to as Dixiecrats, led by Strom Thurmond. Beyond the political party issues, Truman also had to navigate the resistance from organizations like the KKK which extended beyond political discourse into the realm of social unrest and racial violence. Despite these challenges, Truman's civil rights efforts would eventually pave the way for subsequent civil rights legislation.