After the passage of the Kansas–Nebraska Act, Julian became a leader of Indiana's nascent Republican Party, and he won election to the United States House of Representatives in 1860. He helped secure passage of the 1862 Homestead Act and called for the abolition of slavery. He criticized many of President Abraham Lincoln's wartime policies and favored the Wade–Davis Bill over Lincoln's more lenient Reconstruction proposals. He voted in favor of the Thirteenth Amendment, which abolished slavery in the United States and famously feuded with Solomon Meredith, a fellow Hoosier and commander of the Union Army's Iron Brigade during his 1865 re-election campaign.