I've been aware of it for a long time.
Go back and look at Democratic campaigns for the past twenty years. There are a lot more ways to invoke fear in a constituency than by talking about terrorism.
Practically the entire platform of Democratic politics is the idea that if you elect Republicans, something terrible will happen. Social Security will be destroyed. People will starve in the streets. You'll be discriminated against. There's be a religious dictatorship. You'll lose your job. The caribou will die. The forests will burn.
I could go on like this for a whole damn page.
Politics of fear? Are you kidding me?