About two dozen House Republicans delayed a deposition in the ongoing impeachment inquiry on Wednesday, storming the secure hearing room and demanding to take part, raising security concerns about the sensitive space.
After issuing a subpoena to compel Cooper's testimony, Democrats halted the deposition just as it was about to begin and called the House Sergeant-at-Arms, after Republicans forced their way into the secure hearing space that was reserved for members of the three House committees leading the impeachment probe.
The GOP group, led by Reps. Matt Gaetz, R-Fla., staged a news conference denouncing the Democrats' impeachment inquiry before entering the secure room known as a Secure Compartmented Information Facility, or SCIF, where Republicans and Democrats on relevant committees were preparing to question Cooper, a senior Pentagon official with jurisdiction over Russian and Ukrainian policy.
Rep. Gerry Connolly, D-Va., said Republicans "stormed" into the room with their cell phones -- which are not allowed to be in the space that is considered to be the most secure in the Capitol. Some, including Rep. Louie Gohmert of Texas, were shouting.
"The SCIF is used by Congress for lots of classified, highly classified purposes. To compromise that to make a point is deeply troubling," Connolly said. "Failing all else, like the merits of the case, trying to defend the president effectively, they have now decided on physical disruption as their fallback."
Some Democrats challenged the Republicans who entered the hearing room, according to sources.
"Don't you have any work to do today?" Rep. Val Demings, D-Fla., asked Republicans, according to a source familiar with the exchange.
Rep. Mike Conaway, R-Texas, a senior member of the Intelligence Committee, began collecting cellphones from members, who are supposed to deposit them in a cabinet outside before entering the room, according to Connolly and others in the room.
The display forced Capitol Police to sweep the hearing room where Cooper was scheduled to testify. The deposition began around 3 p.m., several hours after it was scheduled to begin and after the protesting Republicans left the secure room.
The Republicans who forced their way into the room argued that they should be able to question the witness even though they aren't members of the committees conducting the impeachment inquiry.
"We are sitting members of Congress," argued Rep. Michael Waltz, R-Fla., "With relevant jurisdiction over the witness."
A House Intelligence Committee official said the House office that provides guidance on rules and procedures had determined that the GOP tactic violated House deposition rules.
More than 45 House Republicans, roughly one in four members of the conference, serve on the House Intelligence, Oversight and Foreign Affairs committees leading the impeachment probe, and have had access to or participated in the inquiry. About one in four House lawmakers serve on the three panels.
Members of the Judiciary Committee, which handles impeachment proceedings, have argued that they should be allowed to take part in the inquiry -- which Democrats have said is a precursor for more formal impeachment proceedings and open hearings.
Cooper did not answer questions from reporters before going behind closed doors to appear in front of the three House committees involved in the impeachment inquiry focusing in part on President Donald Trump's July 25 phone call with Ukrainian President Volodymyr Zekenskiy.
Cooper, who was accompanied by a private lawyer on Wednesday, was the eighth witness to appear for a deposition before House impeachment investigators. She did not read an opening statement to lawmakers and fielded questions surrounding the Trump administration's withholding of nearly $400 million in military assistance to Ukraine this summer.
House Intelligence Committee Chairman Adam Schiff, D-Calif., called Cooper a "real professional who has come forward notwithstanding the obstacles," but did not comment on her testimony.
Cooper's testimony comes one day after the top U.S. diplomat in Ukraine, Ambassador William Taylor, told members of Congress during a closed-door deposition that he believed the Trump administration decided to withhold aid to Ukraine until the country's government agreed to begin an investigation into 2016 election interference and business matters connected to former Vice President Joe Biden's family. One Democrat, Rep. Stephen Lynch of Massachusetts, called the testimony a "sea change" in the impeachment inquiry.
"By mid-July, it was becoming clear to me that the meeting President Zelenskyy wanted was conditioned on the investigation of Burisma and alleged Ukrainian interference in the 2016 U.S. elections. It was also clear that this condition was driven by the irregular channel I had come to understand was guided by Mr. Giuliani," Taylor told Congress, according to his opening statement obtained by ABC News.
Trump took to Twitter on Wednesday to criticize Taylor. He met on Tuesday with members of the conservative House Freedom Caucus -- including participants in Wednesday's demonstration -- at the White House, according to Rep. Mo Brooks, R-Ala.
Trump "was very upbeat about the whole process," Brooks said of the discussion of impeachment. "If you had not known better, you'd have thought he was totally unconcerned about the frivolous nature of the charges leveled by Democrats."
Gaetz said in a statement on Wednesday that he did not visit the White House on Tuesday or discuss the planned demonstration with Trump or other White House officials ahead of time.
ABC News' Jack Arnholz and Luis Martinez contributed to this report.