[83] A House–Senate conference committee proved unable to resolve the disagreements on the bill, and so the entire measure failed.[84] The ensuing debates pitted the northern "restrictionists" (antislavery legislators who wished to bar slavery from the Louisiana territories and prohibit slavery's further expansion) against southern "anti-restrictionists" (proslavery legislators who rejected any interference by Congress inhibiting slavery expansion).[85]
During the following session, the House passed a similar bill with an amendment, introduced on January 26, 1820, by John W. Taylor of New York, allowing Missouri into the union as a slave state. Initially, Monroe opposed any compromise that involved restrictions on slavery's expansion in federal territories. The question had been complicated by the admission in December of Alabama, a slave state, making the number of slave and free states equal. In addition, there was a bill in passage through the House (January 3, 1820) to admit Maine as a free state.[86] Southern congressmen sought to force northerners to accept slavery in Missouri by connecting Maine and Missouri statehood. In this plan, endorsed by Monroe, Maine statehood would be held hostage to slavery in Missouri. 