The Radical Republicans were a faction within the Republican Party originating from the party's founding in 1854—some six years before the Civil War—until the Compromise of 1877, which effectively ended Reconstruction. They called themselves "Radicals" because of their goal of immediate, complete, and permanent eradication of slavery in the United States. They were opposed during the war by the Moderate Republicans, and by the Democratic Party. Radicals led efforts after the war to establish civil rights for former slaves and fully implement emancipation. After unsuccessful measures in 1866 resulted in violence against former slaves in the rebel states, Radicals pushed the Fourteenth Amendment for statutory protections through Congress. They opposed allowing ex-Confederate officers to retake political power in the Southern U.S., and emphasized equality, civil rights and voting rights for the "freedmen", i.e., former slaves who had been freed during or after the Civil War by the Emancipation Proclamation and the Thirteenth Amendment.

The Stalwarts were a faction of the Republican Party that existed briefly in the United States during and after Reconstruction and the Gilded Age during the 1870s and 1880s. Led by U.S. Senator Roscoe Conkling—also known as "Lord Roscoe"—Stalwarts were sometimes called Conklingites. Other notable Stalwarts included Benjamin Wade, Charles J. Folger, George C. Gorham, Chester A. Arthur, Thomas C. Platt, and Leonidas C. Houk. The faction favored Ulysses S. Grant, the eighteenth President of the United States (1869–1877), running for a third term in the 1880 United States presidential election.