Ukraine was always the big black cloud hanging over Joe Biden’s head. It was inevitable that someone was going to use his son’s business activities as evidence that he is a swamp creature who wouldn’t provide enough ethical contrast with Trump to be a suitable Democratic nominee in 2020. The only real questions were who and when.
As it happened, his son is a minor player in a drama that features an abuse of power by Trump. That’s a big break for Biden, and an opportunity. None of the other Democratic candidates are going to touch the issue with a ten foot pole now, and he could end up as a more, not less, sympathetic figure when it is all said and done. It all depends on how he handles it.
My best guess at this point is that Ukraine will move the needle slightly in Warren’s favor, but not much. We’ll see.