Assumption of criminal acts has little basis without substantial evidence to support a charge of a crime committed. It leaves the rule of law behind for the politics of public opinion. In this country a person is innocent until proven guilty beyond the shadow of doubt. And right now under the rule of law, as Barr points out, there is doubt a crime has even been committed.
On top of that there are Trump's job approval numbers backed by a booming economy and historically low unemployment across the board. To impeach a president charges of a crime, not just allegations, must be put forth and job approval numbers in the tank. "Political" evidence from the opposition, belief or opinion that doesn't stand under scrutiny of the rule of law is baseless for the proceedings of impeachment especially when half the public approves of what he's doing.
It's been a smear campaign from the beginning and still is. The people get that. Now, if Biden continues his rhetoric of stopping the fighting, advocating peace and refrains from going off the deep end of hatred for Trump then I do believe he just might give Trump a run for his money come 2020. Thing is, I don't think his base would be happy with the offering of an olive branch.