Comey in October sent a letter to lawmakers about the discovery of new emails the FBI said were potentially relevant to the investigation into Clinton's use of a private email server while serving as secretary of State.
The emails were reportedly found during a separate FBI investigation into former Rep. Anthony Weiner (D-N.Y.). Weiner is the estranged husband of one of Clinton's top aides, Huma Abedin.
Republicans and members of Trump's campaign seized on the new information, attempting to cast Clinton as corrupt and praising the FBI.
Then, just days before the general election, Comey announced the FBI had not changed its July conclusion not to bring charges against Clinton.
Since the election, Clinton campaign officials have put blame on Comey for the Democratic nominee's loss.
Reid has in the past accused Comey of being a "Republican operative."