On the 16th of July, the supplementary Freedmen's Bureau Act was passed over the veto, and on the 24th of July Tennessee was readmitted to representation by a law the preamble of which asserted unmistakably that Congress had assumed control of reconstruction.
Meanwhile the Joint Committee on Reconstruction had made a report asserting that the Southerners had forfeited all constitutional rights, that their state governments were not in constitutional form, and that restoration could be accomplished only when Congress and the President acted together in fixing the terms of readmission.

The uncompromising hostility of the South, the Committee asserted, made necessary adequate safeguards which should include the disfranchisement of the white leaders, either Negro suffrage or a reduction of white representation, and repudiation of the Confederate war debt with recognition of the validity of the United States debt.

These terms were embodied in the Fourteenth Amendment, which was adopted by Congress and sent to the States on June 13, 1866.
In the congressional campaign of 1866, reconstruction was almost the sole issue.

For success the Administration must gain at least one-third of one house, while the radicals were fighting for two-thirds of each House.

If the Administration should fail to make the necessary gain, the work accomplished by the Presidents would be destroyed.