In the moments before Republicans returned to reclaim the House floor late Wednesday night, the scores of Democrats staging a sit-in to demand gun-control votes broke out their simplest props.

Members who were gathered in the well of the chamber began waving 8.5-by-11-inch sheets of white paper, each with the name of someone who died from gun violence, as they broke into the chant that became their anthem during the day: “No bill, no break.”

Their voices steadily rose, reaching a level that was loud enough to drown out Speaker Paul D. Ryan (R-Wis.) when he gaveled the House into session, even though he had the benefit of microphone amplification that Democrats had not enjoyed during their hours-long protest.

Democrats’ decision to seize the floor Wednesday to pressure Republicans to hold votes on gun-control measures after the recent mass shooting in Orlando became a spectacle unlike anything seen in Congress in recent years.

Democrats sang spirituals and told stories about constituents killed in shootings while they angrily denounced their Republican colleagues for their inaction.

When the House TV cameras were turned off, members used their smartphones to broadcast the sit-in via Periscope and Facebook.

“We’ll be here as long as it takes, every day,” House Minority Leader Nancy Pelosi (D-Calif.) said Wednesday afternoon.

House Republicans didn’t think much of the Democrats’ protest, calling it a publicity stunt.

“This isn’t trying to come up with a solution to a problem, this is trying to get attention,” Ryan said Wednesday evening during an interview on CNN, as other Republicans advocated shutting down the chamber and turning off the lights before they rewarded what they saw as Democrats’ bad behavior by giving them the votes they demanded.

The plan for the sit-in began as a hush-hush plot among a few members who huddled in the office of civil rights hero Rep. John Lewis (D-Ga.) on Tuesday night. At first, they worried that Pelosi might disapprove of their plans, Rep. John Yarmuth (D-Ky.) said. But when word leaked, she was on board. What could have been a protest from a few dozen members became a conference-wide commitment.

Members who led the effort said it was never all that organized, and that was partly why they thought it worked so well.

“We wanted to keep it a little organic,” said Yarmuth. Grinning, he added: “It’s cool.”

House Democrats staged a sit-in June 22 for more than 15 hours to try and force a vote on gun control measures. Here's why. (Victoria Walker/The Washington Post)

Much of the day was marked by the carnival atmosphere of an open-mic night.

Lawmakers took turns delivering impassioned speeches as listening members sprawled out on the House floor, leaning against podiums they adorned with rainbow-colored signs saying, “Disarm Hate,” and cheering whenever a Senate Democrat dropped by to offer support.

Sometimes these senators brought snacks to fuel their House colleagues, such as when Sen. Elizabeth Warren (D-Mass.) dropped by announcing, “I just brought Dunkin’ Donuts.”

Rep. Michael E. Capuano (D-Mass.) joked that he had not done something like this since the sit-ins of the 1960s. Rep. Sean Maloney (D-N.Y.) said members should sit on the floor like little kids more often, if it helped them speak from the heart.

Some members even brought blankets, and Rep. Emanuel Cleaver II (D-Mo.) brandished a large pink-striped pillow, as talk turned to occupying the floor throughout the night.

But the tone of the protests themselves were often of bitter pain and anger.

Rep. Bobby L. Rush (D-Ill.) spoke of losing his son to gun violence and discussed hearing the “primal screams” of mothers who had also lost children.

Bad feelings between the two parties bubbled over late at night.

Reps. Louie Gohmert (R-Tex.) and Corrine Brown (D-Fla.) — whose district is home to the gay Orlando nightclub where 49 people were killed earlier this month — nearly got into a physical altercation over who had the right to speak during the protest on the House floor late Wednesday.

Gohmert yelled that the focus should be “radical Islam,” while Democrats said votes on gun-control measures were needed now.

Many Democrats directed their vitriol at Ryan, whom members accused of cowardice and hypocrisy for refusing to schedule gun-control votes.

“Mr. Speaker, where the hell are you?” Rep. John Garamendi (D-Calif.) yelled at one point Wednesday, gesturing toward the empty speaker’s chair. “Are you willing to lead? Are you willing to keep America safe? Or are you hiding, Mr. Speaker, from the responsibility the House gave you?”

Democrats were particularly angry at Republicans for putting the chamber into recess, a move that effectively turned off the cameras that otherwise record all action on the House floor.

Rep. Don Beyer (D-Va.) compared the move to those used by “oppressive governments” in Syria, Iraq and Russia.

“If the Republican cowards who actually run this chamber turned the mics on, we could all be heard a little bit louder,” Rep. Debbie Wasserman Schultz (D-Fla.), who chairs the Democratic National Committee, said in a speech during which she broke into tears.

For much of Wednesday, the House chamber was a scene of utter disorganization.

Senior Democrats ran between the floor and the steps of the Capitol, where protesters offering their support started gathering in midafternoon, trying to build as much public and social media support for the cause as they could.

Republicans scrambled to come up with plans to regain control of the House. Some had a simple idea: If the House was not going to do any work, then turn out the lights, shut off the air conditioning and teach Democrats a lesson as you would a child.

“They will stop this behavior when they think it’s counterproductive instead of productive,” said Rep. Tom Cole (R-Okla.). “If we give in to it, it will be seen as productive. I don’t want to live in a House that runs this way.”

Just after 3 a.m. Thursday, Republicans voted to adjourn the House until after the Fourth of July recess, and Democrats began to congratulate themselves on a hard-fought campaign. But Rep. Maxine Waters (D-Calif.) interrupted the wind-down, pointing out that there were just a few more hours to go until daybreak; she pledged to to stay longer. Several members said they would stick it out with her.

“Just because they have left doesn’t mean we are taking no for an answer,” Pelosi said. “We are not going to stop until the job is done.”

At 6 a.m., about 20 members, including Pelosi, were still on the House floor. Some were wrapped in blankets in the cold chamber — GOP leaders never did turn off the lights or the air conditioning. A few paced to stay awake, and many fought back yawns.

The sit-in was a galvanizing moment for House Democrats, who at the start of the protest seemed surprised at just how much attention their efforts were commanding.

By late Wednesday, they had fully embraced the idea that their protest was not just to raise the profile of gun-control measures. They began likening their efforts to those of leaders of the civil rights movement to give the day a greater meaning.

“Sometimes by sitting down, by sitting in, you’re standing up,” Lewis told House Democrats in one of several speeches he gave to his colleagues. He thanked them for “getting in trouble. Good trouble.”

Lewis was not the only connection to the civil rights movement. When Republicans tried to shut down the Democrats’ protest Wednesday evening, Democrats immediately broke into one of the country’s most recognizable protest songs, which also was a central anthem of the civil rights movement.

“We shall overcome,” they sang, adding several original verses — “We Shall Pass a Bill,” “We Shall End the Hate,” and “We Shall Save the Kids” — to tailor it to the memory of recent mass shootings and the issue of gun control.