Sources close to the White House tell ABC News that Special Counsel Robert Mueller's office responded to President Donald Trump’s legal team late last week regarding a potential interview with the president.

Sources describe a lengthy response from Mueller with a strong emphasis on requesting written answers as it relates to the original mandate of the investigation - Russian meddling in the 2016 elections.

The letter does not mention obstruction — but sources said they believe that will likely be part of negotiations with Mueller's team.

The letter does not take a potential in-person interview with the president off the table, sources say.

The months long negotiations over a potential presidential interview have gone on through several different iterations of the Trump legal team. Current lead attorney, Rudy Giuliani, told ABC News last month that his team had submitted a response to Mueller asking to limit the scope of an interview with Trump especially as it relates to obstruction of justice.

The president has said many times he would be willing to speak with Mueller but would await his legal teams guidance.

Reached by ABC News, the Trump legal team declined to comment.

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