Dana Milbank: On impeachment, the worm has turned

Video: Senator Chris Coons (D-Del.) says reports that President Trump pressured Ukraine to investigate his political rival, former vice president Joe Biden, have raised a new level of concern. If true, Coons says the action would be impeachable. (Joshua Carroll/The Washington Post)(REF:carrollj/The Washington Post)

For months, Democrats agonized over whether to impeach President Trump. Would it cause them to lose House seats? Would it hurt their chances of winning the Senate? Wasn't it pointless because of the near certainty the GOP Senate wouldn't convict him?

But Trump just made the Democrats' choice for them. He left them no alternative but to proceed with impeachment — and they will.

The…