Excerpts from Books and Wikipedia
"Opponents of' the 'slavocracy' of the South created a party in the North to uphold the principle that every man should be free to make himself a good life. It also called for the opening up of the West for small homesteaders. In 1854, the Republican Party was formally founded in Jackson, Michigan, at a meeting of 10,000 people, and the word quickly spread. A leading figure was Abraham Lincoln, who denounced slavery as a breach of the Declaration of Independence." [Furtado: 1001 Days]