[im3w1l]

Imagine a curve. On the x-axis is amount of censorship. On the y-axis is opposition. A slippery slope corresponds to a flat part of the curve, where a large increase in censorship causes a small increase in opposition.

Any policy in the middle of the slippery-slope is not stable. Political alliances are easiest to form advocating either side of it.

In this case there are few people who want Trump banned but think banning Venezuela's National Assembly is a step too far.