Why do you think Monroe opposed the admittance of Missouri
to the Union?

Monroe also feared that northern Federalists were promoting restrictions to Missouri's admittance into the Union because they wanted to split the Jefferson Republicans and make their party a legitimate opposition party again.

one of the main reasons was definitely slavery. back in 1861, republican abraham lincoln was elected and ended up being a major influence in the slavery business. slavery greatly affected the texas economy because back in 1845 during the annexation of texas, slaves became a big part of the texas population. many texans that were in favor of the secession influenced groups through party ties.