What was the question for this implicit rationale, and corresponding answer?
The relevant information is: In 1877, as part of a Congressional bargain to elect Republican Rutherford B. Hayes as president following the close 1876 presidential election, U.S. Army Troops were removed from the South, ending Reconstruction and allowing Democrats to violently suppress Republican voters in order to take power.
The answer: a Congressional bargain to elect Republican Rutherford B. Hayes as president following the close 1876 presidential election
The question: Elected in 1868, Republican President Ulysses S. Grant supported Congressional Reconstruction and enforced the protection of African Americans in the South through the use of the Enforcement Acts passed by Congress. Grant used the Enforcement Acts to effectively combat the Ku Klux Klan, which was essentially wiped out (although a new incarnation of the Klan eventually would again come to national prominence in the 1920s), but was unable to resolve the escalating tensions inside the Republican party between the northerners on the one hand, and those Republicans originally hailing from the South on the other (this latter group would be labelled "Scalawags" by those opposing Reconstruction). Meanwhile, "Redeemers", self-styled Conservatives (in close cooperation with a faction of the Democratic Party) strongly opposed reconstruction. They alleged widespread corruption by the Carpetbaggers, excessive state spending and ruinous taxes. Meanwhile, public support for Reconstruction policies, requiring continued supervision of the South, faded in the North, largely due to concerns over the Panic of 1873. The Democrats, who strongly opposed Reconstruction, regained control of the House of Representatives in 1874. In 1877, as part of a Congressional bargain to elect Republican Rutherford B. Hayes as president following the close 1876 presidential election, U.S. Army Troops were removed from the South, ending Reconstruction and allowing Democrats to violently suppress Republican voters in order to take power.

Answer this question: who or what was responsible for the end of reconstruction?