As a result, Democrats now have a difficult choice to make. The wisest course of action would probably be to drop the complaint as a significant piece of evidence, since it raises almost nothing new. That would be politically embarrassing since they have made so much of it, but they could claim that the whistleblower’s job has been done since it unearthed the alleged wrongdoing and placed it in the public domain.

The alternative course sets the Democrats on a dangerous path. If the whistleblower’s complaint is probative of impeachment, then the whistleblower must testify to find out who gave the person the information that is described. That cannot be done without Republicans present and likely means the whistleblower’s identity must be disclosed. It is one thing to keep that person’s identity secret when the matter is largely handled internally; it is quite another when it is being used to try to remove the democratically elected leader of our nation. The accused must have a chance to confront and cross-examine the witnesses against him, and that right applies as much to Trump as it does to anyone accused of wrongdoing.

Investigation of the whistleblower’s allegations also inserts the House Democrats into the deepest workings of the administration, such as the alleged discussions among White House officials to “lock down” records of the phone call. The president would be remiss if he did not assert executive privilege over these discussions. That will inevitably present Democrats with a Hobson’s choice: Either delay the impeachment hearings to fight such assertions of privilege in court or drop the matter to proceed to a vote without having all the evidence before it. Neither will help them achieve their likely aim: the swift resolution to impeach the president before the election year starts in earnest.