After many years of practicing law in Auburn, he was elected by the state legislature to the U.S. Senate in 1849. Seward's strong stances and provocative words against slavery brought him hatred in the South. He was re-elected to the Senate in 1855, and soon joined the nascent Republican Party, becoming one of its leading figures. As the 1860 presidential election approached, he was regarded as the leading candidate for the Republican nomination. Several factors, including attitudes to his vocal opposition to slavery, his support for immigrants and Catholics, and his association with editor and political boss Thurlow Weed, worked against him and Abraham Lincoln secured the presidential nomination. Although devastated by his loss, he campaigned for Lincoln, who was elected and appointed him Secretary of State.