The founder of the Republican Party in the United States is often credited to a coalition of anti-slavery activists, former Whigs, and Free Soil Democrats, with key figures like Horace Greeley, who helped establish the party in 1854. The party emerged in response to the Kansas-Nebraska Act and aimed to combat the spread of slavery into western territories. Its first presidential candidate was John C. Frémont in 1856, and it evolved into a significant political force by the time Abraham Lincoln was elected as the first Republican president in 1860.