Editor’s Note: This story has been updated with the Justice Department’s response to House Judiciary Chairman Jerry Nadler.

The Justice Department is bracing for impact. Acting Attorney General Matt Whitaker is set to testify before Congress on Friday, but now says he will not show up unless Democrats promise not to subpoena him during his testimony.

In a letter sent to House Judiciary Chairman Jerry Nadler Thursday afternoon, Justice Department legislative affairs chief Stephen Boyd said that if Nadler doesn’t make this promise in writing by 6 p.m. Thursday, then Whitaker will be a no-show at the hearing.

In the Department’s sprawling Pennsylvania Avenue headquarters, dozens of officials have been working to get him ready for the testimony he may now skip. The hearing would be the first blockbuster showdown between the Trump administration and oversight-antsy Hill Democrats who just recently secured the power to force the president’s allies to testify. And now, it may not even happen.

Rep. Eric Swalwell, a Democrat on the committee, took a jab at Whitaker on Twitter after the news of broke. “Not how it works,” he wrote.

Democrats want Whitaker to talk about Trump's reported efforts to influence Justice Department investigations involving him and his businesses—namely, Mueller's Russia probe and the Southern District of New York investigation. If Whitaker refuses to answer those questions, they may consider subpoenaing him.

In the letter, Boyd said Whitaker is ready to tell Congress that he has never made any promises to President Donald Trump regarding Special Counsel Robert Mueller’s Russia probe.

“The Acting Attorney General will testify that at no time did the White House ask for, or did the Acting Attorney General provide, any promises or commitments concerning the Special Counsel’s investigation,” Boyd wrote.

The letter came shortly after the House Judiciary Committee voted along party lines to authorize Nadler to subpoena Whitaker if he so chooses. In the letter, Boyd called this move “an attempt to circumvent the constitutionally required accommodation process and thereby to transform the hearing into a public spectacle.” He added that Nadler was demanding “confidential presidential communications that no Attorney General could ever be expected to disclose under the circumstances.”

A person familiar with Whitaker’s preparation told The Daily Beast he has been gearing up for an intense few hours.

“They hate this guy so much,” the source said.

Whitaker has gone through multiple practice committee hearings—known as moots—where Justice Department officials pepper him with questions that committee Democrats may lob, according to multiple DOJ officials involved in his preparation. They have tried to prepare him for lengthy statements, harsh tones, and leading questions. Dozens of department officials have helped him prepare, those officials told The Daily Beast, working through the government shutdown to brief him and get him ready. And they’ve been gearing up for questions about Special Counsel Robert Mueller’s Russia probe, according to one source familiar with Whitaker’s preparation, including whether he had input on the investigation’s resources.

“We don’t know what we’re up against with the House Judiciary Committee,” that source said. “We have no idea.”

A senior Justice Department official concurred.

“We don’t know what they’re going to do,” that official said.

Nadler, meanwhile, appeared to spend the weeks before the scheduled testimony laying the groundwork for a court fight. His spokesperson, Daniel Schwarz, said Whitaker should know exactly what’s coming.

“The notion that Mr. Whitaker doesn’t know what to expect on Friday is absurd,” Schwarz said. “We have given him months to prepare for this hearing, provided him with a list of questions more than two weeks ago, and we continue to give our Republican colleagues every opportunity to weigh in on the process. Most importantly, in repeated public letter after public letter, we have made our expectations for Mr. Whitaker’s appearance crystal clear. If he is still confused at this point, it is because he hasn’t done his homework—not because we haven’t explained it to him.”

On Jan. 22, Nadler sent Whitaker a letter listing questions he plans to ask, including about his talks with President Donald Trump before he fired Jeff Sessions and his role supervising Mueller’s Russia investigation. And, importantly, Nadler also asked Whitaker to tell him at least 48 hours before the hearing if he planned to invoke executive privilege in response to any of those questions. Executive privilege refers to the president’s legal right to have private conversations with his staff about his presidential duties. Though the Constitution doesn’t use the term, the Supreme Court has ruled that this right exists.

The Justice Department did not make Nadler’s 48-hour deadline.

“We’re not aware of any rules that govern a set amount of time when one needs to invoke executive privilege,” one senior DOJ official involved in Whitaker’s preparation told The Daily Beast.

Nadler’s little-noticed 48-hour request could be significant. If Whitaker refuses to answer questions without invoking executive privilege, the committee could potentially move to hold him in contempt of Congress and then ask a federal judge to force him to answer their questions. The fact that Nadler has told Whitaker what he plans to ask and has requested notice of any executive-privilege claims means a federal judge may be more likely to side with a potential Democratic effort to compel testimony.

“One thing the court looks at is, were people trying to play nice and work this out before they came to us?” said a former congressional staffer who requested anonymity because of the sensitivity of the discussions. “Did they try and figure this out before they came here? The committee has put itself on a better footing, already trying to work this out with Matt Whitaker before he shows up. That will matter to a court when it comes to enforcing a contempt resolution, which would essentially be asking the court to compel him to answer the questions.”

Nadler is laying the groundwork for a potential court fight. If Whitaker doesn’t show up on Friday , they could serve him with a subpoena. If he defies the subpoena, the House of Representatives could ask a federal judge to enforce it.

Justice Department officials, meanwhile, have been preparing for this tactic, according to one source who spoke with The Daily Beast. They have reviewed the ways Nadler’s committee could try to make Whitaker answer questions.

Nadler’s legal machinations have irked DOJ officials.

“It’s unfortunate that they decided to engage in this kind of political theatrics, especially given the fact that this is someone who has voluntarily agreed to come in,” the senior official said. “We’ve never seen this before.”

But the former congressional staffer said this step is necessary because Trump administration officials have stiff-armed Congress in prior testimony.

“It’s a deviation from the norm that is a direct reaction to the administration’s witnesses’ deviations from the norm of either answering a question or asserting a valid privilege,” the former staffer said. “‘I kind of think there might be a privilege and don’t want to answer the question because the president might tweet about me’ is not a valid privilege.’”

Any hope Whitaker harbors for reprieve from committee Republicans may be misplaced. Though Whitaker has endeared himself to Trump, he has not charmed those House conservatives who have scrutinized how the Justice Department secured a warrant to secretly surveil former Trump campaign adviser Carter Page. Republicans have been arm-wrestling the Justice Department for two years now as they try to secure internal communications and witness testimony about the department’s investigation of the Trump campaign. Former Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein often stiff-armed the conservative firebrands. And Whitaker––despite having made a host of public statements criticizing Mueller before becoming attorney general––hasn’t been much different.

“There are Republicans who believe that Whitaker has been no better than Sessions when it comes to cooperating with reasonable oversight,” said one Republican member of the committee.