Reconstruction in the years following the Civil War saw a contest between duelling factions for control over the reassembly of the Union. The era can be divided into two periods: Presidential Reconstruction and Congressional, or Radical Reconstruction.
President Lincoln had already begun to consider how best to reconstruct the Union two years before Lee's surrender at Appamatox in 1865. Lincoln favored very much of a "forgive and forget" approach to admitting the seceded states back into the Union. His Ten-Percent Plan in 1864 advocated readmission for a state when ten percent of its residents had taken an oath of allegiance (essentially planning never to do it again). This legislation represented a kinder, gentler form of Reconstruction with fewer hoops through which to jump. The Wade-Davis Bill in 1864 was Congress's reaction to Lincoln's Ten-Percent Plan. Instead of only ten percent, the Wade-Davis Bill asserted that fifty percent of a state's residence must take an oath of allegiance in order for a state to even begin rewriting its constitution. Readmission would not happen until the constitution was written and approved by Congress. Even in this early stage of Reconstruction, the tactics with which the President and Congress pursued the readmission of the seceded states were quite different.
Each faction had different resources from which to draw. Congressional Reconstruction drew primarily from the power of Congress itself. It had the ability to make laws, and the President was in very little position to stop them - even when Lincoln was President. The President, on the other hand, drew much of his support from the people, as they wanted to see an end of the war and the restored Union. Ultimately, Congress's tactics and resources won out after Lincoln was assassinated in 1865 and President Johnson's presidency proved extremely ineffective. The source of conflict between the two parties sprung from the different attitudes towards the seceded states. While the President was more forgiving, Congress was far more harsh and did not want to make readmission a walk in the park for the South.