There is stuff like cynicism and complacency.
I guess they could be much stronger.
High voter satisfaction - high positive complacency bringing it lower.
You are used to new status quo, you like it.
Low voter satisfaction - high negative complacency bringing approval higher.
Despite that voters would join pressure group - implement suggested policies or else we’ll spread misinformation (which is damaging for lots of stuff) or even join terrorist groups.
Those with highest income would have lobbying power too - I suggested mechanic like that.
I also suggested mechanic that interacts with voter apathy