Richard Pilger, the current chief of the DOJ Elections Crime Branch of the department's Public Integrity Section, engaged in discussions in 2010 and 2013 with Lerner and other IRS officials about ways to pursue criminal prosecutions of conservative nonprofits, the records show.

"Whistleblowers allege that Washington Field Office Assistant Special Agent in Charge Timothy Thibault disregarded agency guidelines requiring substantial factual predication to trigger investigations, while declining to move forward with other investigations despite proper predication," the senator wrote.

"Thibault and Richard Pilger, director of the election crimes branch within the FBI's public integrity section, reportedly were instrumental in the opening of an investigation into the Trump campaign and its associates based in substantial part on information from left-aligned organization," he added. "Whistleblowers claim that Thibault, Pilger and others didn't always adhere to agency policies in their supervision of various election-related matters, including campaign finance investigations across multiple presidential election cycles."