Answer:
Radical Republicans in Congress were most responsible for the passage of the Fourteenth Amendment, as they wanted to guarantee political rights for African Americans as soon as posible after the end of the Civil War.
Explanation:
The Fourteenth Amendment to the Constitution of the United States is one of the post-Civil War amendments, and includes, among others, the Due Process Clause and the Equal Protection Clause. It was proposed on June 13, 1866, and ratified on July 9, 1868.
The amendment provides a broad definition of national citizenship, which overrides the decision of Dred Scott v. Sandford (1857), which had excluded slaves and their descendants from possessing constitutional rights. It requires states to provide equal protection before the law to all persons (not just citizens) within their jurisdictions. The importance of the Fourteenth Amendment was exemplified when it was interpreted to prohibit racial segregation in public schools in Brown v. Board of Education.
The other two post-war amendments are the Thirteenth Amendment (prohibiting slavery) and the Fifteenth Amendment (it prohibits qualifications regarding the vote determined by race).
