WASHINGTON — As the impeachment inquiry moves into a critical week, President Trump and his Republican allies are debating the degree to which the president should participate in a process they have spent more than two months attacking.

On Sunday evening, White House counsel Pat Cipollone told the House Judiciary Committee in a five-page letter that Trump would not participate in its first impeachment hearing, scheduled for Wednesday. The invitation from Chairman Jerrold Nadler “does not begin to provide the President with any semblance of a fair process,” Cipollone wrote.

Four constitutional scholars – three chosen by Democrats, one by Republicans – are expected to testify on the standards for impeachment. Nadler, D-N.Y., told Trump he had until 6 p.m. Sunday to notify the committee that he or his attorneys would attend; he has given Trump until Friday to decide whether to participate more broadly in the impeachment process.

In his letter Sunday, Cipollone did not rule out participating in future hearings but asked Nadler to detail his plans for the upcoming proceedings, including whether he would allow further testimony and cross-examination of fact witnesses, among them those who already testified before the House Intelligence Committee. He also said Republicans should be able to call additional witnesses.

“Even at this late date, it is not yet clear whether you will afford the President at least these basic, fundamental rights or continue to deny them,” Cipollone wrote.

Nadler spokesman Daniel Schwarz declined to comment on Cipollone’s letter.

The Trump administration’s response suggests it will continue taking a defiant approach to the impeachment proceedings, betting that Republicans will stick together behind a noncooperation strategy meant to cast the inquiry as a partisan “witch hunt.” The move comes as Democrats on the House Intelligence Committee prepare to meet Tuesday to approve the release of their report detailing the panel’s findings on Trump’s dealings with Ukraine.

On Sunday, Democrats called on the White House to cooperate, suggesting an innocent person would have no problem testifying.

“We’re certainly hoping that the president, his counsel, will take advantage of that opportunity if he has not done anything wrong,” Rep. Val Demings, D-Fla., said on ABC News’s “This Week.” “We’re certainly anxious to hear his explanation of that.”

But there is a conflict inside the GOP over the extent to which Trump and his congressional defenders ought to engage, even as Republicans signaled that they will continue their aggressive campaign to delegitimize the process as corrupt and unfair.

Speaking on “Fox News Sunday,” Rep. Douglas Collins of Georgia, the top Republican on the Judiciary Committee, said he understood why the White House might want to skip the Wednesday hearing, calling it “just another rerun” covering ground already surveyed in previous Judiciary Committee hearings.

“This is a complete American waste of time right here,” he said.

But he added that Republicans would be more keen to participate in future hearings – particularly one examining the findings of the House Intelligence Committee as prepared by its chairman, Rep. Adam Schiff, D-Calif. The committee is scheduled to meet Tuesday to approve the report’s release.

Other Republican lawmakers said Trump could benefit from availing himself of the due-process protections that Nadler has offered, including the right to present evidence, suggest witnesses and cross-examine those called by Democrats to testify.

Rep. Tom McClintock, R-Calif., a Judiciary Committee member, said on “This Week” that he thought it “would be to the president’s advantage” to have counsel participate in the upcoming hearings. “But I can also understand how he is upset at the illegitimate process that we saw unfold in the Intelligence Committee,” he said.

The president did not address the issue himself Sunday. He sent two tweets about World AIDS Day in the early afternoon and spent a second day in a row at his golf course in West Palm Beach, Florida, after returning early Friday from a Thanksgiving visit to U.S. troops in Afghanistan.

In the past, however, Trump has suggested he would like to participate. Last month he said he would “love” for several senior administration officials to testify in the impeachment inquiry, but he contended that the White House was preventing them from doing so to protect the institution of the presidency.

“The D.C. Wolves and Fake News Media are reading far too much into people being forced by Courts to testify before Congress,” Trump said in a tweet on Tuesday. “I am fighting for future Presidents and the Office of the President. Other than that, I would actually like people to testify.”

On Sunday, Republicans renewed attacks on the impeachment process, a likely preview of what’s to come this week.

Collins attacked the timeline that Democratic leaders are pursuing, one that appears aimed at concluding an impeachment vote in the House before Christmas, rather, he argued, than providing appropriate due process for the president.

“They want to get this president right now before everybody completely sees through the process sham,” Collins said. “So we’re rushing this.”

On Sunday, he called for Schiff personally to testify, indicating that the Intelligence Committee chairman would face intense questioning from Republicans on the role his panel played in shepherding the whistleblower complaint that exposed Trump’s irregular dealings with Ukraine, among other matters.

The Republican congressman noted that Schiff has compared the panel’s fact-finding process with that of the independent prosecutors who examined matters that led to impeachment proceedings against Presidents Richard Nixon and Bill Clinton. In those cases, Collins noted, those prosecutors subjected themselves to congressional questioning.

“He’s put himself into that position,” Collins said. “It’s easy to hide behind a report. It’s easy to hide behind a gavel and the Intelligence Committee’s behind-closed-door hearings. But it’s going to be another thing to actually get up and have to answer questions.”

Another Republican, Rep. Andy Biggs of Arizona, predicted that the impeachment inquiry will take a turn for the combative this week, when it moves to the Judiciary Committee.

“It’s a bunch of brawlers sometimes on the Judiciary Committee, so it should get pretty hot and under the collar as we go along,” Biggs, who sits on the panel, said in an interview with Fox News Channel’s Mike Emanuel on “Sunday Morning Futures.” “I don’t think things have been done the way they’ve been done in the past, Mike, and so it causes some rancor and it should be pretty – much more feisty, I would say, than the Intel Committee was.”

Democrats on the Judiciary Committee, meanwhile, said Sunday that Republicans were trying to distract from Trump’s wrongdoing by raising objections to the impeachment process without challenging the facts that have been gathered.

Demings said Democrats were “not going to play any games” with Republicans and called on Trump to end his stonewall of the Democrats’ witness and document demands.

“They want to … play a political game and tie the process up in the courts as long as they can and run the clock out,” she said. “We’re not willing to play that game.”

Sen. John Kennedy, R-La., meanwhile, argued that both Russia and Ukraine interfered in the 2016 presidential election, despite the intelligence community’s assessment that only Russia did so.

The comments mark Kennedy’s latest attempt to shift the focus away from the U.S. intelligence community’s conclusion that Russia worked to help elect Trump, following a Fox News Channel interview last week from which he later backtracked.

“I think both Russia and Ukraine meddled in the 2016 election,” Kennedy told host Chuck Todd on “Meet the Press” on Sunday.

Todd pressed Kennedy on whether he was concerned that he had been “duped” by Russian propaganda, noting reports that U.S. intelligence officials recently briefed senators that “this is a Russian intelligence propaganda campaign in order to get people like you to say these things about Ukraine.”

Kennedy responded that he had received no such warning.

“I wasn’t briefed. Dr. Hill is entitled to her opinion,” Kennedy said, referring to former National Security Council Russia adviser Fiona Hill, who testified in the impeachment inquiry last month.

In her public testimony, Hill warned that several Trump allies had spread unfounded allegations that Ukraine, rather than Russia, had interfered in the 2016 U.S. presidential election.

“This is a fictional narrative that has been perpetrated and propagated by the Russian security services,” she said.

The Washington Post’s Abigail Hauslohner contributed to this report.