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(CNN) —  

A federal judge will consider a lawsuit over a key White House official’s House subpoena in mid-December, meaning some key impeachment witnesses like former national security adviser John Bolton may be beyond the reach of Democrats as they try to rapidly pursue their investigation of the President.

Former deputy national security adviser Charles Kupperman had run to the courts last Friday asking for help deciding whether he needed to appear for scheduled testimony Monday on Capitol Hill. He did not show up Monday.

The federal judge, Richard Leon of the DC District Court, brought Kupperman’s attorneys, the House and the Justice Department into court Thursday because the urgency of the situation. Still, the court detour means the case may lag behind and impact action on the Hill.

By mid-December, the House of Representatives may already be well into public hearings about Trump’s actions and moving toward voting to impeach.

But the court’s schedule may allow Kupperman and potentially Bolton and others to avoid testifying.

Kupperman was on the line during Trump’s July call with Ukrainian President Volodymyr Zelensky. Bolton is at the center of several key events related to the impeachment inquiry, including reportedly raising concerns about Trump’s dealings with Ukraine.

Chuck Cooper, the defense attorney for both Kupperman and Bolton, wouldn’t say on Thursday whether Bolton will sue like his former deputy has. The judge pointed out that if he did, he would likely make similar legal arguments.

Kupperman filed a lawsuit last week because he couldn’t decide whether to comply with the House subpoena this week or with the White House’s order for him not to testify, claiming he had immunity. Bolton is scheduled for a deposition in the house for next Thursday.

The House is moving as swiftly as it can through the closed-door depositions, and Democrats say they will begin public hearings soon, potentially before Thanksgiving, although the timing remains fluid.

If that timeline holds, however, Democrats could begin drafting or even considering articles of impeachment by the time the court hearing occurs.

Judge Leon told the Justice Department, the House of Representatives and Kupperman’s lawyers that he will hear arguments on December 10 about the court’s role in the dispute.

When a Justice Department attorney asked for more time next month to respond to arguments in the case, Leon chastised her.

“When it’s a matter of this consequence…You roll your sleeves up, you get the job done. If you can’t do it I’m sure your colleagues can,” Leon said.

He called the lawsuit over Kupperman’s testimony a “matter of great public interest and a matter of great urgency for the country.”

In the legal fight over Kupperman’s testimony, a major question will be whether Kupperman can even sue, and whether the court has a role to play in this case.

A lawyer for the House of Representatives argued on Thursday this isn’t a legitimate case. Kupperman’s attorney Cooper noted that the Justice Department was arguing in another hearing down the hall in the DC federal courthouse – about the House subpoena of former White House attorney Don McGahn – that federal judges should stay out of fights between the two other branches of government.

Cooper said he believed the court should take this case.

But he said he wouldn’t side with the White House’s immunity assertion or with the House subpoena, when the case got to that point. “We have no dog in the merits fight, your honor,” Cooper said.

Todd Tatelman, a lawyer for the House, called Kupperman’s lawsuit one that “serves no other purpose than to attempt to delay” the House’s inquiries.

The judge responded by saying this lawsuit could potentially be more efficient, especially compared to holding Kupperman in contempt of Congress, then Congress suing him.