How could both the North and the South fear that the other was gaining too much power prior to the Civil War? Why did Northern states feel threatened by the “Slave Power,” or political power slave st

How could both the North and the South fear that the other was gaining too much power prior to the Civil War?

 Why did Northern states feel threatened by the “Slave Power,” or political power slave states held in Congress? 

Consider issues/events such as the Gag Rule, rapid expansion, popular sovereignty, the tougher fugitive slave law of 1850, the Kansas-Nebraska Act, Bleeding Kansas, Bleeding Sumner, and the Dred Scott court case. On the other hand, what exactly did the Republicans stand for, and why did Southern states react by seceding after Abraham Lincoln’s election? Consider the debate over the abolition, containment, and expansion of slavery.