Rumors circulated throughout the campaign of 1858 that Lincoln was a member of the American Party, also known as the Know Nothing Party. Since the latter was a secret order, it was difficult to determine who belonged to it. Rumors that Lincoln was a member cost him political support in part due to the party’s anti-immigrant, anti-Catholic stance. He even lost the political loyalty of long-time friend and former Whig James L. D. Morrison, who was married to a Catholic and concerned about Lincoln’s purported connections to the Know Nothings. Nevertheless, for a time, Lincoln did not speak publicly on the issue since doing so could also have potentially cost him support among undecided American Party voters, who were a critical contingent in the elections of 1858—particularly in central Illinois, where they were concentrated in a few counties and wielded significant influence. Douglas and other Democrats courted American Party supporters heavily throughout the 1858 campaign, in part by appealing to racism and portraying Lincoln and other Republicans as proponents of social and political equality of the races.

Despite his long public silence on the topic, in 1855 Lincoln had declared in a letter to friend Joshua F. Speed that he was not a Know Nothing, asking, “How can any one who abhors the oppression of negroes, be in favor of degrading classes of white people?”

In Illinois’s local elections of 1858, Republicans won a majority of all votes cast in the state, but pro-Douglas Democrats retained control of the Illinois General Assembly and Douglas ultimately won reelection to the U.S. Senate. Despite his loss, Lincoln’s participation in the senate race—and in the Lincoln-Douglas Debates in particular—propelled him to national prominence and helped him win the presidential contest of 1860.