Final answer:
Northerners accused Southerners of a 'slave power conspiracy' involving an attempt to spread the South's agrarian ideals and protect the institution of slavery, escalating sectional tensions.
Step-by-step explanation:
Northerners accused Southerners of engaging in a "slave power conspiracy" to impose aristocratic, agrarian ideals on the rest of the nation. This term reflects the northern perception that an elite class of wealthy planters in the South held disproportionate political power and sought to spread the institution of slavery and its associated economic and social systems. The conflict arose from divergent economic interests; the South with its plantation economy demanded low tariffs, whereas after an economic panic, northerners supported higher tariffs and land grant measures to stabilize and develop the economy. The South viewed these measures as a threat that could promote an antislavery agenda, escalating sectional tensions between the two regions.