<P> When free - soil Maine offered its petition for statehood , the Senate quickly linked the Maine and Missouri bills , making Maine admission a condition for Missouri entering the Union with slavery unrestricted . Senator Jesse B. Thomas of Illinois added a compromise proviso , excluding slavery from all remaining lands of the Louisiana Purchase north of the 36 ° 30 ' parallel . The combined measures passed the Senate , only to be voted down in the House by those Northern representatives who held out for a free Missouri . Speaker of the House Henry Clay of Kentucky , in a desperate bid to break the deadlock , divided the Senate bills . Clay and his pro-compromise allies succeeded in pressuring half the anti-restrictionist House Southerners to submit to the passage of the Thomas proviso , while maneuvering a number of restrictionist House northerners to acquiesce in supporting Missouri as a slave state . The Missouri question in the 15th Congress ended in stalemate on March 4 , 1819 , the House sustaining its northern antislavery position , and the Senate blocking a slavery restricted statehood . </P>
who was the skilled politician behind the missouri compromise
Speaker of the House Henry Clay of Kentucky