Rep. Devin Nunes sent a letter to House Intelligence Committee Chairman Adam Schiff demanding he provide a closed-door testimony on his conversations with the whistleblower whose complaint launched impeachment proceedings against President Trump.

Nunes, the highest-ranking Republican on the House Intelligence Committee, said Schiff, who has held all hearings in the early process of impeachment, must disclose his own involvement with the whistleblower behind closed doors.

"On November 6th, you announced the beginning of public hearings associated with the Democratic Party's partisan impeachment inquiry into President Donald J. Trump," Nunes said in a Friday letter. "Based on the precedent and lack of jurisdiction, the House Intelligence Committee should not take the lead in conducting such hearings; however, by now the American people know your desire to see the duly-elected president removed from office outweighs your sense of responsibility to running a functioning intelligence oversight committee."

He added, "Prior to the start of your public show trial next week, at least one additional closed-door deposition must take place. Specifically, I request that you sit for a closed-door deposition before the House Intelligence, Foreign Affairs and Oversight Committees."

Schiff has been under scrutiny from Republican lawmakers who feel that his efforts to impeach Trump have been molded by a partisan interest as a Democrat in removing the president from office. A group of House Republicans stormed a closed-door testimony being conducted by Schiff and the Intelligence Committee last month, claiming they were not being properly informed of the information obtained in the impeachment process.

Nunes also asserted that Schiff became a key impeachment figure when "you and/or your staff met with or talked to" the whistleblower who complained that a July 25 phone call between Trump and Ukrainian President Volodymyr Zelensky reflected a quid pro quo. While only Schiff's staff know the identity of the whistleblower, 33-year-old Eric Ciaramella, a career intelligence analyst, has been alleged in many reports of being the whistleblower.

Ciaramella was Ukraine director on the National Security Council during the end of the Obama administration and remained there during the start of the Trump administration when he was briefly acting senior director for European and Russian affairs. The Washington Examiner reported on Oct. 7 that Ciaramella is now a deputy national intelligence officer for Russia and Eurasia on the National Intelligence Council, reporting to the director of national intelligence. His identity remains unconfirmed.

Schiff claims to have had no direct contact with the whistleblower, but he faced criticism after it was revealed the whistleblower privately met with an intelligence panel aide seeking guidance before filing the complaint about Trump's Ukraine communications with the Intelligence Community inspector general, and Schiff knew about it but did not immediately inform his Republican colleagues on his panel.

In his Friday letter to Schiff, Nunes demanded the chairman reveal the details of the August contact between the whistleblower and the House Intelligence Committee.

"Although you publicly claim nothing inappropriate was discussed, the three committees deserve to hear directly from you the substance and circumstances surrounding any discussions conducted with the whistleblower, and any instructions you issued regarding those discussions," said Nunes. "Given that you have reneged on your public commitment to let the committees interview the whistleblower directly, you are the only individual who can provide clarity as to these conversations."