As for the difficulties in abolitionist movement, slave owners who employed slave labor in the Americas strongly resisted abolitionist efforts. Social tension and instability created by employer who employed slave labor became more and more serious. Unlike the case in Europe, slavery in America was a domestic institution in the United States and was primarily under local (state) control, slaveholders often dominated the country 's national government. Employers of slave labor feared for their own safety if the slaves were freed. Due to the import of large number of slaves, several regions had slave majorities. Slave owners worried that if slaves were suddenly freed, they might take over or exact revenge on their former masters. Although abolitionism