Short answers, pulled from the story.
The Crittenden Compromise was a package of six constitutional amendments and four resolutions designed to permanently enshrine slavery within the United States Constitution. The proposal aimed to make it unconstitutional for future congresses to ever end the institution of slavery.
The core of the compromise drew a line at latitude 36 degrees 30 minutes north across the map to mandate permanent slavery south of this parallel while prohibiting it north of that line in all territories. This plan extended the old boundary westward into New Mexico Territory and Indian Territory.
President-elect Abraham Lincoln vehemently opposed the Crittenden Compromise because he opposed any policy permitting the continued expansion of slavery. He wrote to key Republican leaders including William Seward stating he would entertain no proposition for a compromise regarding the extension of slavery.
Congress tabled the document without a vote on the 31st of December 1860 after both houses rejected the measures during the final session prior to inauguration. The Senate rejected the proposal after it had been introduced on December 18 and the House also turned down the measures.
Delegates at the Peace Conference of 1861 attempted to revive the compromise but ultimately failed to avert secession between February 8 and 27 1861 in Washington D.C. The meeting served as the final formal effort of the states to avoid war before the failure marked the end of serious legislative attempts to prevent conflict through compromise.