House Republicans are talking about wrapping up their investigation into Russia’s campaign meddling despite protests from Democrats that three high-profile witnesses close to President Donald Trump are stiff-arming efforts to question them.

Former White House chief strategist Steve Bannon, former Trump campaign manager Corey Lewandowski, and departing White House communications director Hope Hicks have each declined in separate interviews with the Intelligence Committee to talk about certain matters, in some cases saying the president may want to assert executive privilege over their discussions later.

“If you were going to design this investigation for failure, that’s what they’d be doing,” Democrat Mike Quigley said in an interview, referring to the Republican talk of closing the probe. “It’s like the president is coordinating with them in this effort.”

The most recent witness to balk at some questions was Hicks, who spent almost nine hours before the Intelligence panel on Tuesday. On Wednesday, she announced she is stepping down. She has told friends that she has been mulling her future for months.

As Bannon did last month, Hicks told the House panel that she had instructions from the White House to not answer questions on some topics concerning the transition before Trump took office or anything from her tenure in the administration. Lewandowski is refusing to discuss any matters after his departure from the Trump campaign in June 2016, including conversations with the president.

Committee Democrats say members must force these witnesses to testify more fully if the panel’s investigation into Russian interference in the 2016 campaign and potential collusion with anyone close to Trump is to be thorough and seen as credible. They say Republicans aren’t energetically challenging questionable claims of privilege from the former aides and aren’t helping to secure production of other information, including banking and travel documents.

“The integrity and independence of the committee and Congress’ investigative and enforcement powers are at stake,” said the top Democrat on the panel, Adam Schiff.

Neither committee Chairman Devin Nunes nor the Republican colleague he picked to lead the panel’s Russia investigation, Michael Conaway, returned messages asking for comment.

But other Intelligence panel Republicans acknowledge that even they haven’t been brought into any committee meetings on pursuing contempt of Congress charges or other action to compel more witness cooperation.

Rep. Tom Rooney, one of the two Republicans assigned as the main witness interviewers in the probe, acknowledged on Tuesday that there are “legitimate questions” that need to be answered eventually about what the committee intends to do “for the sake of this body and the committees that have subpoena power” and “whether or not those subpoenas be taken seriously in the future.”

But Rooney stopped short of saying additional legal action should be taken.

“Let’s finish the investigation,” Rooney said. “We’re almost, I think, nearing the end.”

Quigley said that if the Republicans do move soon to shut down the probe, Democrats will counter the majority’s committee report on the investigation’s findings with one of their own that would point out information that should have been sought and obtained, but wasn’t.