Rep. Elijah Cummings, the highest-ranking Democrat on the House Oversight Committee, asked the State Department to provide lawmakers with a copy of an email exchange between Hillary Clinton and Colin Powell, in which Powell purportedly advised Clinton on her use of personal email.

The Jan. 23, 2009, exchange was a central component of the explanation Clinton gave FBI investigators last month as to why she set up the private email server.

But the law enforcement agency did not include it in the classified notes from its year-long investigation of Clinton, which members received on Aug. 16.

"Rather than clarifying this situation, the information provided to Congress by the FBI raises even more questions than it answers," Cummings wrote in a letter Monday to Secretary of State John Kerry,

The Maryland Democrat blasted the "internally contradictory" classification process that the administration applied to Clinton's emails. He pointed to records that were explicitly marked unclassified at the time they were written, only to be classified retroactively and redacted by the State Department during its review of the emails for release to Congress and, eventually, the public.

Clinton's latest defense of her private email use — that she did so at the behest of Powell — has been called into question.

The Democratic nominee reportedly told FBI investigators during an interview that Powell advised her to use a personal server during a 2009 dinner party.

However, Powell has since told reporters he has no recollection of that conversation.

Rep. Jason Chaffetz, the Republican chairman of the Oversight committee, has also pushed the State and Justice departments for more information based on questions raised by the FBI's notes, including whether Clinton's attorney enjoyed unauthorized access to classified records that sat on a thumb drive in his desk drawer for months.