Final answer:
Radical Republicans advanced for black Americans by advocating for their rights, passing legislation to protect freedmen and grant them voting rights, and pushing for policies that promote racial equality.
Step-by-step explanation:
The characteristics of radical Republicans advanced for black Americans by advocating for their rights and actively working towards creating a more equal society. Radical Republicans in Congress passed legislation to protect freedmen and grant them voting rights, which helped to build a new powerful voting bloc. They also pushed for policies such as integrating schools and redistributing plantation lands to empower black Americans and promote racial equality. In contrast, by the mid-20th century, notions of "Black capitalism" and self-reliance put forth by conservatives within the Republican Party became significant. This aligned with elements of Black Nationalism, suggesting economic betterment could be achieved through hard work and self-discipline, as advocated by figures like Booker T. Washington. The strategy of supporting Black self-help and economic autonomy was seen as a means for the Republicans advance into traditionally Democratic neighborhoods and voting blocs, despite varying results and criticisms.