FBI agents charged with investigating Hillary Clinton’s private emails server knew for weeks that investigators had discovered potential new evidence against her during a separate investigation, but waited to brief FBI Director James Comey, according to a report from the Washington Post.

Comey wrote to members of Congress Friday informing them the FBI had discovered information “pertinent” to their probe of Clinton’s private server and that he thought his bureau should take "appropriate investigative steps designed to allow investigators to review these emails."

Comey said that he learned of the new information on Thursday and promptly felt “obligated” to write congressional investigators to inform them about the new developments.

However, because of the timing of Comey’s letter — just 11 days before Election Day — he immediately came under fire from Democrats, especially Clinton’s campaign. They alleged that Comey’s decision to write Congress was politically charged.

Comey wrote his letter at the objection of Attorney General Loretta Lynch, who advised him to follow longstanding Department of Justice policy and not potentially interfere in the upcoming presidential election.

Given that the agents knew of the emails for weeks, its not yet clear why they waited so long before telling Comey.

According to the Post, agents discovered the messages soon after the FBI had seized devices belonging to former Congressman Anthony Weiner.