Former Trump campaign adviser George Papadopoulos arrives at a closed-door hearing before the House Judiciary and Oversight Committee Oct. 25 in Washington. (Alex Wong/Getty Images)

George Papadopoulos, a former Trump campaign adviser who pleaded guilty to lying to the FBI, is asking a federal judge to keep him out of prison until a constitutional challenge to the special counsel investigation of Russian interference in the 2016 election is resolved.

In a motion filed Friday, Papadopoulos’s lawyers revealed that he has been ordered to report to serve his 14-day sentence on Nov. 26.

Papadopoulos’s brief stint in prison would bring to a close a key piece of special counsel Robert S. Mueller III’s investigation. A tip that Papadopoulos was told by a professor in London in April 2016 that the Russians had dirt on Democratic presidential candidate Hillary Clinton, in the form of thousands of emails, helped spark the first investigation into the Trump campaign and Russia in July 2016.

Papadopoulos’s lawyers argued Friday that he is not a flight risk and that little harm would result from allowing him to put off his prison sentence until a case that could invalidate his conviction is resolved.

A three-judge panel for the U.S. Court of Appeals for the D.C. Circuit heard arguments earlier this month in the case, which involves a former assistant to Trump confidante Roger Stone who has been subpoenaed to provide testimony in front of Mueller’s grand jury.

The assistant, Andrew Miller, has refused to comply. His legal team has argued Mueller’s appointment was unconstitutional because Mueller’s authority is too broad and his work has too little oversight from the Department of Justice.

Miller’s lawyers contend that Mueller’s authority has made him essentially akin to a “principal officer” under the Constitution, which would require confirmation by the Senate.

Attorneys for Mueller have argued that he is in fact an “inferior officer,” like other Justice Department officials, and that his work has been supervised by an official appointed by the president and confirmed by the Senate, Deputy Attorney Gen. Rod J. Rosenstein.

It is not yet clear how arguments in the case might be affected by President Trump’s replacement of former attorney general Jeff Sessions, who had recused himself from the investigation, with acting attorney general Matthew G. Whitaker, who has not gone through the confirmation process. Mueller and Miller have until Monday to file additional briefs on how Whitaker’s appointment affects the case.

Regardless of how the appeals court panel rules, the issue could ultimately be considered by the Supreme Court.

Two federal judges at the district court level have ruled that Mueller’s appointment was constitutional in other cases, but Miller’s case is the first to be reviewed at the higher appellate level.

Papadopoulos waived his right to appeal his conviction when he pleaded guilty last year. But his attorneys argued that should Mueller’s appointment be ruled unconstitutional, the finding would amount to new evidence that would allow for him to move to have his conviction tossed.

“The question on appeal is not frivolous. George deserves the benefit of waiting for the court of appeals’ decision before reporting to serve his sentence,” Caroline Polisi, a lawyer for Papadopoulos, said in a statement. “There’s absolutely no harm in staying his sentence in order to see the outcome of this case. If the Mueller appointment is found to be unconstitutional, there is obviously a very strong argument for invalidating George’s conviction.”

Papadopoulos’s conversation with a professor in London about Russia and Clinton came months before emails allegedly hacked by Russian intelligence were publicly released through WikiLeaks. Papadopoulos recounted the tip to an Australian diplomat, who in turn told American officials — launching the first investigation into the Trump campaign and Russia in July 2016.

Papadopoulos told a judge in September that he was remorseful for lying to the FBI about certain details of his encounter with the professor and two Russians to whom the professor introduced him. He told the judge that he made a “a terrible mistake, for which I have paid a terrible price, and am deeply ashamed.”

More recently, he has been active on Twitter, alleging that he was set up by Western intelligence.

This week, he replaced the Chicago-based lawyers who helped him negotiate his plea deal with Mueller with a new team from the Los Angeles-based firm Pierce Bainbridge Beck Price & Hecht, suggesting he had new plans to fight his conviction.