A former top aide to Hillary Clinton admitted in March 2015 that the campaign could not answer difficult questions about Clinton's private email use in the days after the New York Times exposed it for the first time.

Philippe Reines, a former State Department aide to Clinton who recently played the role of Donald Trump during her debate preparations, admitted to other high-level campaign staffers on March 7 of last year that allies' suggestions for mitigating the controversy did not seem effective.

"There Is Just No Good Answer," he wrote.

Anne-Marie Slaughter, a longtime Clinton ally who also served in the State Department for part of Clinton's tenure, had offered to place an op-ed defending Clinton's private email use "from the point of view of a former State Dept [sic] official."

"Moreover, the overall lesson that everyone had taken away from the Clinton administration was not to put ANYTHING politically sensitive on email period, regardless of the system," Slaughter said.

The email chain was published by WikiLeaks on Wednesday in the 19th batch of Clinton campaign emails dumped online to date. WikiLeaks claims it had obtained 50,000 emails from the inbox of John Podesta, Clinton's campaign chair.

Reines' admission emerged a day after the transparency website published conversations between Podesta and Neera Tanden, co-chair of Clinton's transition team, that indicated Clinton's inner circle of aides and lawyers had not been forthcoming about the unauthorized server system because "they wanted to get away with it."

Other emails released since the Podesta records first appeared on Oct. 7 show Clinton's aides labored over the precise wording of her statements about the server in the immediate aftermath of the Times story.