(CNN) George Papadopoulos, the former Trump campaign adviser who pleaded guilty to lying to the FBI, is making his first appearance testifying on Capitol Hill later this month.

Papadopoulos is expected to testify behind closed doors before a small group of lawmakers on the House Judiciary and Oversight committees on October 25, according to two sources familiar with the matter.

The interview is part of Judiciary Chairman Bob Goodlatte and Oversight Chairman Trey Gowdy's investigation into the FBI's handling of the Hillary Clinton email and Russia investigations, although Democrats are likely to press the former Trump foreign policy adviser on potential Russia collusion, too.

Papadopoulos has also been in discussions with the Senate Intelligence Committee for an interview, according to one of the sources. And California Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, has expressed a desire to speak to Papadopoulos as part of his investigation into potential collusion between Trump's team and Russia. Schiff and the House Intelligence Committee Democrats interviewed Papadopoulos' wife, Simona Mangiante Papadopoulos, in July.

A committee aide said the panel's Democrats are still interested in talking to Papadopoulos and "look forward to scheduling an interview at the appropriate time."

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