House Judiciary Committee Chairman Jerrold Nadler is preparing to subpoena acting attorney general Matthew G. Whitaker to testify before the panel about whether his relationship with President Trump influenced his oversight of the special counsel’s Russia probe if Whitaker does not agree to testify voluntarily in January.

“One could conclude that he is stalling,” Nadler (D-N.Y.) said Tuesday, stressing that the panel had been working since late November to set an interview date with Whitaker. “If we don’t reach a date in the next day or two, we will subpoena him.”

Nadler said he expects to inform Whitaker of his intentions in a letter that committee Democrats plan to send to him Wednesday. But they insist they will keep pressing Whitaker to testify, even if he attempts to avoid the subpoena, and regardless of whether Whitaker is still running the Justice Department by the time they can bring him to Capitol Hill.

Scheduling Whitaker’s testimony has been a top priority for Nadler, but doing so has been complicated by a combination of factors, including the impending confirmation of attorney general nominee William P. Barr and the fact that House Democratic leaders still have not appointed rank-and-file members to their committees. Until the House Judiciary Committee is constituted, which Nadler said he does not expect to happen until next week at the earliest, any plans to hold hearings with witnesses are effectively on hold.

Justice Department officials have cited the partial government shutdown as a reason they have, thus far, not been able to commit to an interview date — an explanation that rankles Democratic leaders who suspect Whitaker is trying to stall until he is no longer in office.

“If it’s important enough, they can find a couple of hours sometime in January — especially since they were on notice since November,” Nadler said, adding that Whitaker’s departure from the Justice Department would not absolve him of scrutiny for the months he has overseen special counsel Robert S. Mueller III’s probe, despite a recommendation from the agency’s ethics office to recuse himself.

Kerri Kupec, a Justice Department spokeswoman, said the department “offered dates in February contingent on government reopening and two-week window post-opening for prep. Fourteen days’ notice is standard and consistent with what we ask for with hearings.”

She said the Justice Department had not heard back from Nadler since acknowledging a letter from him and proposing two possible dates for testimony.

Barr’s confirmation process begins in the Senate Judiciary Committee on Tuesday, and if the past is precedent, he could be confirmed to his position by early next month. The Senate confirmed his predecessor, Jeff Sessions, to be attorney general a month after his initial hearing in 2017, and that was after a delay to accommodate Democrats’ requests for more time to review his materials.

Leading congressional Republicans say the commencement of Barr’s confirmation process next week obviates the need for continued scrutiny of Whitaker.

“At this point in time, the Senate has started moving on its confirmation process,” House Judiciary ranking Republican Douglas A. Collins (Ga.) said in a statement. “Bringing Whitaker in would show that the Democrats are focused on chasing rabbits down a hole when we should be focusing on the confirmation of a new, permanent attorney general and what that means for the Justice Department going forward.”

Whitaker came to the helm of the Justice Department days after the midterm election, following Sessions’s ouster. A few days after that, House Democrats sent the first of several letters to the Justice Department, demanding to know whether Whitaker could preside over the Mueller probe free from bias, given how emphatically he had decried it before he took the job.

House Judiciary Democrats say that the Justice Department has been slow to respond to their requests for most information and documents but acknowledge the shutdown bears some blame for that.

Whitaker has never been accused of a specific instance of wrongdoing, and Mueller’s team has continued to release indictments since Whitaker’s appointment in November. But that has not assuaged Democrats’ concerns that he was in a position to limit the reach of Mueller’s probe.

Among the sources for the Democrats’ concerns were Whitaker’s public statements from before he took over from Sessions, urging that the investigation be either restricted or defunded. Nadler and other leading Democrats also openly wondered whether Whitaker might defer to Trump before making decisions regarding the probe or otherwise coordinate with the White House to ensure the president had access to information that might enable Trump to circumvent certain lines of inquiry.

House Democrats leading the Judiciary Committee have stated that protecting Mueller’s ability to operate unfettered is a top priority; a bill to give the special counsel recourse to file a court challenge against any potential effort to terminate his position is also among the panel’s top targets for the new year.

It is unclear how fully Republicans will be on board with those efforts.

Most congressional Republicans have balked at efforts to pass a special counsel protection bill, citing constitutional concerns with legislation that would guarantee judicial review for hiring and firing decisions that fall under the president’s executive authority.

Republicans have also been absent thus far from Democrats’ efforts to compel the Justice Department to turn over outstanding documents requested last year, even when the requests were bipartisan.

Matt Zapotosky contributed to this report.