What is one reason that northerners lost interest in reconstruction?

Economic problems began to sap at the North’s effort for an effective reconstruction.  Even public support for reconstruction starts to decline.  At this point, Southerners call for an end to the Reconstruction.  Though support was now declining, Congress was still able to enact the Civil Rights Act of 1875 as part of its efforts to implement the terms of the 14th and 15th Amendments.

fourteenth amendment