Evil, wickedness and depravity have that power and sway over sinners, just as sin has dominion over mortals.
As for the relatively small group of conservative party politicians and activist who will leave the conservative party over the issue, they will remain relatively small in number and influence.
Satan and sin are involved in this spiritual battle and they will have power and influence on the nation mainly because of ignorance and apathy.
Why is this happening now??
It is a sign of the times we live in. And these are the end times of creation. There is worse to come.
Prov 29:16 When the wicked are multiplied, transgression increaseth: but the righteous shall see their fall.
Psalm 12:8 The wicked walk on every side, when the vilest men are exalted.