WASHINGTON — House Republicans ground the impeachment inquiry to a halt for hours on Wednesday, staging a protest at the Capitol that sowed chaos and delayed a crucial deposition as they sought to deflect the spotlight from the revelations the investigation has unearthed about President Trump.
Chanting “Let us in! Let us in!” about two dozen Republican members of the House pushed past Capitol Police officers to enter the secure rooms of the House Intelligence Committee, where impeachment investigators have been conducting private interviews that have painted a damaging picture of the president’s behavior.
They refused to leave, and the standoff in the normally hushed corridors was marked by shouting matches between Republican and Democratic lawmakers and an appearance by the House sergeant-at-arms, the top law enforcement official in the chamber.
After waiting about five hours for the protest to break up, Laura K. Cooper, the deputy assistant secretary of defense for Russia, Ukraine and Eurasia, answered questions for more than three hours before the panel wrapped up its work for the day.
“This is a Soviet-style process,” declared Representative Steve Scalise, the No. 2 House Republican. “It should not be allowed in the United States of America. Every member of Congress ought to be allowed in that room. The press ought to be allowed in that room.”
Roughly a quarter of House Republicans are members of the three panels conducting the inquiry, and have been allowed to participate in the private depositions and interviews from the start. But most of the Republicans who rushed the secure rooms on Wednesday morning are not committee members.
The protest came a day after the most damning testimony yet about Mr. Trump’s pressure campaign to enlist Ukraine to smear his political rivals, which unfolded even as Mr. Trump met privately at the White House with ultraconservative Republicans who promised aggressive measures to defend him against the impeachment onslaught.
In his testimony on Tuesday, William B. Taylor Jr., the top American diplomat in Kiev, effectively confirmed Democrats’ main accusation against Mr. Trump: that the president withheld military aid from Ukraine in a quid pro quo effort to pressure that country’s leader to incriminate former Vice President Joseph R. Biden Jr. and smear other Democrats.
Ms. Cooper appeared under subpoena, in defiance of the Defense Department, which has said it would not cooperate in the inquiry. Lawmakers said her testimony was less dramatic and more technical than Mr. Taylor’s, and gave a narrower view of the suspension of aid at the heart of the inquiry. But Representative Adam B. Schiff, Democrat of California and the Intelligence Committee chairman, who is leading the inquiry, said the panel was “grateful that the witness is a real professional and has come forward notwithstanding the obstacles.”
Across the Capitol, leading Republican senators who have become resigned to the prospect of serving as jurors in the impeachment trial of their party’s president were struggling to explain away the revelations about Mr. Trump.
“The picture coming out of it, based on the reporting that we’ve seen, I would say is not a good one,” Senator John Thune of South Dakota, the No. 2 Senate Republican, told CNN. “But I would say also that until we have a process that allows for everybody to see this in full transparency, it’s pretty hard to draw any hard and fast conclusions.”
On Tuesday, Senator Mitch McConnell of Kentucky, the majority leader, denied that he had told Mr. Trump that a telephone call the president had with President Volodymyr Zelensky of Ukraine was “perfect” and “innocent.” The call is a crucial focus of the inquiry, and Mr. Trump had said that Mr. McConnell had told him he approved of it. Mr. McConnell said he could recall no such conversation.
Indeed, some Republicans are growing increasingly uneasy about the inquiry, and fretting that it could get much, much worse for them. Publicly, they are taking their cues from the president, and Wednesday’s performance appeared intended to please Mr. Trump. The president has fumed publicly and privately that Republicans have not been tough enough in defending him, and has recently tried to undercut the inquiry by suggesting that the whistle-blower whose allegations touched it off is not credible or does not exist.
“Where’s the Whistleblower?” the president tweeted on Wednesday.
On Wednesday, the senior Republicans on the three investigative panels involved in the inquiry formally requested that Mr. Schiff arrange for public testimony by the whistle-blower, and all government officials the whistle-blower relied on to compile that account.
Representatives Jim Jordan of the Oversight and Reform Committee, Devin Nunes of the Intelligence Committee and Michael McCaul of the Foreign Affairs Committee wrote to Mr. Schiff that the testimony was needed to “fully assess the sources and credibility of the employee,” given what they called “inconsistencies between facts as alleged by the employee and information obtained during the so-called impeachment inquiry.”
But some Republicans concede privately that it is difficult to mount an effective defense of Mr. Trump when much of the testimony and evidence available paints an unfavorable picture of the president, and there are few witnesses they could call who could credibly refute the accounts of a stream of administration officials who have testified.
The result has been a haphazard approach by Republicans defined mostly by public spectacles like Wednesday’s scene, which even some in the party said crossed the lines of propriety.
“This is nuts, they’re making a run on the SCIF,” said Senator Lindsey Graham, Republican of South Carolina, a close ally of Mr. Trump, referring to the Secure Compartmentalized Information Facility where the intelligence panel meets. “That’s not the way to do it.”
Mr. Graham later backtracked on Twitter, saying Republicans had been peaceful in their protest, and adding, “I understand their frustration and they have good reason to be upset.”
The pandemonium unfolding in the Capitol came amid other fast-moving developments in the inquiry. A federal judge ordered the State Department on Wednesday to release records related to Ukraine within 30 days to a government watchdog group.
And impeachment investigators leveled new demands of the State Department, requesting access to a relatively narrow set of communications, notes and memorandums related to Ukraine that could bolster damning witness testimony. Among the documents in question are summaries of key executive branch meetings, and diplomatic cables about Mr. Trump’s decision to freeze $391 million in security assistance for Ukraine.
The House, meanwhile, passed its third piece of legislation — the Shield Act — aimed at preventing foreign interference in American elections. But Mr. McConnell has indicated that he will not bring it up for a vote, and Mr. Trump threatened to veto it.
The day began with House Republicans rushing to Mr. Trump’s defense as the president has publicly demanded. About 9:45 a.m., not long after Ms. Cooper arrived, a parade of House Republicans, led by Representative Matt Gaetz of Florida, marched into the bowels of the Capitol where a phalanx of reporters and television cameras were gathered outside the secure rooms.
One by one, they denounced the inquiry as a “sham,” in the words of Representative Andy Biggs of Arizona, as they demanded access to the room. Representative Earl L. “Buddy” Carter of Georgia issued a dire warning: “If a government can do this to the president of the United States, they can do it to you as well. You need to be scared. You need to be very scared.”
When they were done, they stalked off, barging through the ordinarily closed double doors into the secure space. Some brought their cellphones, which is not permitted and considered a security breach. Representative Bennie Thompson, the chairman of the House Homeland Security Committee, later wrote to the sergeant-at-arms, asking him to “take action” against Republicans for what he called a “blatant breach of security.”
The standoff stretched into the afternoon as protesting Republicans ordered pizza and fast food for the throng of reporters assembled to witness their demonstration. Democrats noted that some of the protesting lawmakers were on relevant committees — and thus had the right to attend the deposition. Eventually, lawmakers were summoned to the House floor for a vote, which put an end to the sit-in.
Democrats said the timing of the protest was no coincidence, given Mr. Taylor’s testimony on Tuesday. They characterized the Republican disruption — “sit-in, stand-in, call it whatever you want,” said Representative Harley Rouda, Democrat of California — as a desperate attempt to deflect attention from the damaging testimony.
“They crashed a room where there were a bunch of Republicans getting ready to question a witness,” said Representative Jamie Raskin, Democrat of Maryland, adding, “Their attempt to act like Freedom Riders is really an attack on the committee system in Congress.”
At the White House, Mr. Trump took to Twitter to assail Mr. Taylor and his lawyer, John Bellinger — and to offer encouragement to Republican protesters.
“Never Trumper Republican John Bellinger, represents Never Trumper Diplomat Bill Taylor (who I don’t know), in testimony before Congress!” the president wrote. “Do Nothing Democrats allow Republicans Zero Representation, Zero due process, and Zero Transparency.”
For weeks now, lawmakers on the three House committees involved in the inquiry have been conducting private question-and-answer sessions, which have produced a stream of compelling testimony from government witnesses, much of it confirming and expanding on the whistle-blower complaint.
Those sessions are attended by both Democrats and Republicans, and both have an opportunity to question witnesses; more than 100 of the 435 members of the House are eligible to participate. Democrats have said that they plan to hold open hearings after the committees finish deposing witnesses, and that they intend to make public complete transcripts of witness testimony after they have been reviewed for classified material.
For now, however, the inquiry has unfolded entirely behind closed doors, as has been the case in the preliminary stages of past congressional investigations conducted by members of both parties, including the one Republicans opened during the Obama administration into the attack on American diplomatic facilities in Benghazi, Libya, in 2012.
Emily Cochrane, Catie Edmondson and Michael D. Shear contributed reporting.