Republican Party nomination

Republican National Convention met in mid-May, the Democrats had been forced to adjourn their convention in Charleston after 57 ballots. William H. Seward of New York was considered the frontrunner, followed by Abraham Lincoln of Illinois, Salmon P. Chase of Ohio, and Pennsylvania's Simon Cameron.
As the convention developed, however, it was revealed that Seward, Chase, and Cameron had each alienated factions of the Republican Party. Delegates were concerned that Seward was too identified with the radical wing of the Republican Party, and Seward's moves toward the center had alienated the radicals. Chase, a former Democrat, Cameron had little support outside Pennsylvania and was distrusted by many former Whigs because he had switched from the Whig Party to the Democratic Party before becoming a Republican.
It was essential to carry the West, and because Lincoln had a national reputation from his debates and speeches as the most articulate moderate, he won the party's nomination. The party platform clearly stated that slavery would not be allowed to spread any farther, and also promised that tariffs protecting industry would be imposed.