The Republican Party, of which I am a member, stands pledged since 1856 to the extermination, so far as the federal government has the power, the twin relics of barbarism, slavery, and polygamy. They have this power in the territories of the United States.

As quoted in His Brother's Blood: Speeches and Writings, 1838–64 (2004), edited by William Frederick Moore and Jane Ann Moore, p. 192 - Speech to the U.S. House of Representatives (April 1860)