What event following Abraham Lincoln's assassination raised concerns among the Radical Republicans about the future of the nation and the process of Reconstruction?

Formation of the Freedmen's Bureau
Andrew Johnson's presidency Andrew Johnson's presidency

The event that raised concerns among the Radical Republicans about the future of the nation and the process of Reconstruction was Andrew Johnson's presidency. Johnson's lenient approach towards the former Confederate states and lack of protection for freed slaves led to fears that the South would not be adequately reconstructed and that the rights of African Americans would not be upheld. This ultimately led to conflicts between Johnson and the Radical Republicans in Congress, and a more assertive approach towards Reconstruction.