WASHINGTON - A group of House Republicans barged into a secure room at the Capitol on Wednesday where the latest witness in the Democrat-led impeachment inquiry was set to testify, temporarily shutting down the proceedings.

The disruption delayed closed-door testimony from Laura Cooper, the Pentagon official who oversees Ukraine policy, whom lawmakers planned to ask about the White House's decision to withhold military aid for several months over the summer.

Earlier Wednesday, President Donald Trump lashed out anew at "terrible" Democrats a day after damaging testimony from a key diplomat in the Ukraine controversy. William Taylor, the acting U.S. ambassador to Ukraine, had testified Tuesday that Trump wanted military aid to Ukraine linked to the country's willingness to investigate the 2016 election and former vice president Joe Biden and his son Hunter Biden.

Democrats decried the Republican shutdown of Wednesday's planned testimony by Cooper, dismissing it as a stunt.

"It's totally inappropriate," said Rep. Harley Rouda, D-Calif., who watched the episode unfold. "When the facts are against you, when the law is against you . . . you're left arguing process."

Rep. Ted Lieu, D-Calif., called the Republicans' actions "a violation of House rules."

"They can't just crash into this," Lieu said.

A group of about two-dozen Trump allies stormed a room in the Capitol basement where three investigative committees were supposed to hear testimony from Laura Cooper, the Pentagon official who oversees Ukraine policy. Those members were not on the committees of jurisdiction and were not supposed to be present during the closed-door deposition.

A shouting match began between Rep. Louie Gohmert, R-Texas, and some Democrats in the room as House Intelligence Committee Chairman Adam Schiff, D-Calif., left to consult with the sergeant at arms, according to Rep. Gerald Connolly, D-Va., who witnessed the entire episode.

Cooper was slated to begin testimony at 10 a.m. but was still being held in a private room off the secure area.

The protest was part of a Republican effort to change the narrative from the substance of the allegations against Trump to complaints about the process. Republicans have accused Democrats of trying to conduct a secretive takedown of the president by investigating behind closed doors; Democrats say, however, that they will open up the process for public hearings in a matter of weeks after they conduct their investigation.

Democrats are now looking at whether they will have to physically remove Republican members from the room. They may instead reschedule the deposition and have Capitol Police guard the doors to block entry.

Republicans broke the rules when they followed lawmakers into the locked facility and brought their phones into the secretive space. All electronics are barred from the secure area, which is meant for discussing highly sensitive or classified information.

Earlier, Trump lashed out at Democrats in a spate of tweets and retweets that stretched past midnight, with many focusing on the fact that Democrats are conducting depositions during the impeachment inquiry behind closed doors.

"The Witch Hunt continues!" Trump said in one tweet in which he shared House Minority Whip Steve Scalise, R-La., accusing Democrats of "using shady backroom tactics completely out of the public eye."

"The Democrats Scam goes on and on! They Do Nothing!" Trump said in another tweet in which he shared Rep. Robert Aderholt, R-Ala., complaining that the "impeachment process is literally being conducted in the basement of the Capitol, behind closed doors" and calling it "a mockery."

In a tweet of his own, Rep. Bobby Rush, D-Ill., characterized Trump's missives as "rage-tweeting at midnight."

Trump returned to Twitter shortly before dawn on Wednesday, picking up where he left off.

"It never ends. The Do Nothing Dems are terrible!" he said in one tweet.

In another, he asked, "Where is the Whistleblower?" and asserted, "The Do Nothing Dems case is DEAD!"

Trump then retweeted an assessement by former acting attorney general Matthew Whitaker: "This #impeachment is not a constitutional process but an unprecedented #Democrat attack on a #Republican @POTUS"

Democratic leaders have likened this stage of the impeachment inquiry to grand jury proceedings and have said they are conducting depositions behind closed doors so that witnesses are less likely to be aware of one another's testimony.

Both Democrats and Republicans and their staff have participated in the questioning.

Democrats have said it may no longer be necessary for the whistleblower whose complaint sparked the inquiry to testify given firsthand witnesses who are corroborating what he relayed.

Also Wednesday, Democratic presidential hopeful Beto O'Rourke said Wednesday that Trump made the ultimate case for why he is not fit for office when he compared the impeachment proceedings to a lynching in a tweet this week.

"If you had not been convinced of how unfit he is to lead this country, his invocation of lynching to describe what is happening to him in a fair, deliberate, democratic process, that should convince you beyond a shadow of a doubt," O'Rourke said at a Washington Post Live event Wednesday morning.

O'Rourke said that he was recently in Montgomery, Alabama, and visited a memorial that has the name of every African American who was lynched at a time when terror was used "to keep people down, through lynchings, through burnings, through drownings, through beatings."

“To have the most privileged, the most powerful white man on the face of the planet invoke that same word to describe what is happening to him is one of the most obscene things that I’ve heard in American life in my lifetime,” O’Rourke said. “And it goes to show the extent to which he will lie, the extent to which he will commit these obscenities.”