The correct answer is: Republicans disagreed with President Johnson's Reconstruction Plan.
After President Lincoln's assassination, President Andrew Johnson's approach to Reconstruction was seen as too lenient towards the South. This led to significant conflict with the Republican-controlled Congress, which sought to implement a more stringent Reconstruction policy that aimed to protect the rights of freed slaves and ensure a more comprehensive rebuilding of Southern society. The disagreements over their respective visions for Reconstruction ultimately led to a significant power struggle between Johnson and Congress.