Warrant Related to Clinton Emails to Be Unsealed Tuesday

The warrant authorized the FBI search of a laptop in final days before election.

But the possibility that emails discovered on the laptop could be related to the investigation led Comey to issue a stunning letter to Congress on Oct. 28, informing them of the rekindled probe.

"In connection with an unrelated case, the FBI has learned of the existence of emails that appear to be pertinent to the investigation," Comey wrote in the letter to Congress.

Nine days later, on Nov. 6, just two days before the election, Comey said in another letter to Congress, "Based on our review, we have not changed our conclusions that we expressed in July with respect to Secretary Clinton."

A top donor told ABC News that the Comey letter was "a perfect setup for failure."