The New York American, or Know Nothing, Party held its annual Grand Council in Albany on August 24, 1858. At the meeting, the waning third party set their annual state convention for September 8 in Syracuse to coincide with the Republican convention and pave the way for a possible alliance. While the majority of council members approved of an American and Republican alliance, about a quarter of the council rejected Republicans for their history of outspoken disdain for nativism.

The American and Republican conventions on September 8 commenced with a positive outlook toward a unification. Both parties agreed on a platform that softened antislavery rhetoric and hinted at nativism. However, last minute changes to the platform by a Republican committee infuriated the Americans and the chance of a union was destroyed. The American Party put forth their own nominations despite the reality that they would never have the support to win any office.

Abraham Lincoln was the Republican candidate from Illinois for the U.S. Senate. At this time the Illinois General Assembly elected the state’s representatives in the U.S. Senate, thus the outcome of races for the Illinois House of Representatives and Illinois Senate were of importance to Lincoln’s campaign. Lincoln campaigned extensively in Illinois in the summer and fall of 1858, delivering speeches and campaigning on behalf of Republican candidates for the General Assembly. He and his opponent, Democrat Stephen A. Douglas, the incumbent, both focused their campaign efforts on the former Whig stronghold of central Illinois, where the state legislative races were the closest. Among the former Whigs whose votes were courted were those who had moved into the American Party following the dissolution of the Whig Party. Former members of the American Party, often referred to colloquially as "Fillmore Men" because the national party backed Millard Fillmore in the presidential election of 1856, were an important source of votes for both Democrats and Republicans in the state and federal elections of 1858, and both Lincoln and Douglas worked hard to garner their support. In state elections of 1856, Madison County had sent two American Party members to the Illinois House of Representatives, and in the presidential contest, Bond, Madison, and Montgomery counties gave Fillmore 46.4, 39.3, and 37.2 percent of the vote, respectively. Lincoln expressed his concern in a previous letter to Gillespie that the overwhelming number of votes cast for American Party candidate Millard Fillmore in the 1856 presidential election in the Twenty-First District meant that a large number of voters could now be swayed to vote either Democrat or Republican. In statewide local elections, Republicans gained a majority of the votes, but Pro-Douglas Democrats retained control of the General Assembly, and Douglas won re-election. Madison County sent Democrats Zephaniah B. Job and Joseph H. Sloss to the Illinois House, and Democrat Samuel A. Buckmaster defeated Gillespie by 184 votes in the Senate District Twenty-One. Buckmaster, Job, and Sloss all voted for Douglas in the Senate election. See 1858 Illinois Republican Convention; 1858 Federal Election.