<Li> The Wilmot Proviso, which was created by Congressman David Wilmot, banning slavery in any new territory to be acquired from Mexico, not including Texas which had been annexed the previous year . Passed by the United States House of Representatives in August 1846 and February 1847 but not the Senate . Later an effort to attach the proviso to the Treaty of Guadalupe Hidalgo also failed . </Li> <Li> Failed amendments to the Wilmot Proviso by William W. Wick and then Stephen Douglas extending the Missouri Compromise line (36 ° 30' parallel north) west to the Pacific, allowing slavery in most of present - day New Mexico and Arizona, Las Vegas, Nevada, and Southern California, as well as any other territories that might be acquired from Mexico . The line was again proposed by the Nashville Convention of June 1850 . </Li> <Li> Popular sovereignty, developed by Lewis Cass and Douglas as the eventual Democratic Party position, letting each territory decide whether to allow slavery . </Li> <Li> William L. Yancey's "Alabama Platform," endorsed by the Alabama and Georgia legislatures and by Democratic state conventions in Florida and Virginia, called for no restrictions on slavery in the territories either by the federal government or by territorial governments before statehood, opposition to any candidates supporting either the Wilmot Proviso or popular sovereignty, and federal legislation overruling Mexican anti-slavery laws . </Li>

What is the significance of the mexican cession