<P> In 1848 , the Treaty of Guadalupe Hidalgo ending the war was submitted to the Senate for approval . Douglas , now in the Senate , was among those who joined with the South to defeat an effort to attach the Wilmot Proviso to the treaty . In the prior year 's debate in the House , Douglas had argued that all of the debate over slavery in the territories was premature ; the time to deal with that issue was when the territory was actually organized by Congress . Lewis Cass ( Democrat ) in December 1847 , in his famous letter to A.O.P. Nicholson in Tennessee , further defined the concept of popular sovereignty which would soon evolve as the mainstream Democratic alternative to the Wilmot Proviso : </P>
<P> In 1848 , the Treaty of Guadalupe Hidalgo ending the war was submitted to the Senate for approval . Douglas , now in the Senate , was among those who joined with the South to defeat an effort to attach the Wilmot Proviso to the treaty . In the prior year 's debate in the House , Douglas had argued that all of the debate over slavery in the territories was premature ; the time to deal with that issue was when the territory was actually organized by Congress . Lewis Cass ( Democrat ) in December 1847 , in his famous letter to A.O.P. Nicholson in Tennessee , further defined the concept of popular sovereignty which would soon evolve as the mainstream Democratic alternative to the Wilmot Proviso : </P>
who proposed a counter proposal to the wilmot proviso
who proposed a counter proposal to the wilmot proviso
Lewis Cass
Lewis Cass