Although I can't find it through a Google search, I do remember a study done on this.

500 people, half Democrats, half Republicans. They all were shown two competing health care plans. Half were told Plan A was from the Democrats and Plan B was from the Republicans. The other half were told the exact opposite.

Didn't matter the plan or the person, over 75% of all Republicans and Democrats strongly defended "their" party's "plan" and attacked the other.

Proves it's not the action most people judge, but who did the action. And we're seeing it in spades with impeachment. If anyone seriously thinks that if President Hillary Clinton would be getting impeached today while doing the exact same thing Trump did to get impeached, they're not dealing in reality.