You know exactly what the reaction is going to be.

"I'm not sure what the political or economic reaction is going to be," he added.

This reaction will probably go away in a couple of months.

They would come in tired at evening, and then the reaction might go the other way.

"Probably a natural reaction to what we went through today."

I don't know what the reaction is going to be.

This reaction is usually not serious and generally goes away within 3 hours.

So it is not clear just what specific reactions might be going on.

But at least one can attempt to say what form the reaction is going to take.