The House erupted in chaos Thursday morning with Democrats crying foul after Republicans hastily persuaded a few of their own to switch their votes and narrowly block an amendment intended to protect lesbian, gay, bisexual and transgender people from discrimination.

It was an unruly scene on the floor with Democrats chanting, “Shame!” after GOP leaders barely muscled up the votes to reject, 212-213, an amendment by Rep. Sean Patrick Maloney (D-N.Y.) that would have effectively barred federal contractors from getting government work if they discriminate against the LGBT community.

At one point, a monitor in the House gallery showed there were 217 votes supporting the legislation, eliciting cheers of joy from Democrats who thought the measure might actually pass. But over the course of about 10 minutes, those votes suddenly dropped one by one to 212 — and the amendment failed.

A number of lawmakers from western states, who originally voted yes, changed their votes. According to a list tweeted out an hour after the vote by House Minority Whip Steny Hoyer’s (D-Md.) office, they included: California Reps. Darrell Issa, David Valadao, Jeff Denham, Mimi Walters, and Rep. Greg Walden of Oregon, Rep. David Yong of Iowa and Rep. Bruce Poliquin of Maine. Their offices have not yet responded to a request for comment

Maloney, the amendment’s author, was furious with Republicans for how they handled the floor fight over his offering. He singled out Majority Leader Kevin McCarthy (R-Calif.) in particular for criticism, saying the No. 2 House Republican personally lobbied GOP members to change their votes when it looked like Maloney’s proposal would pass.

“The leader [McCarthy] went around and twisted their arms, and they voted for discrimination,” Maloney said. When Maloney complained directly to McCarthy, he said the majority leader told him “to get back on your own side.”

“The members who switched are going to hold a very special place in American history as the people who didn’t have the guts to stand up and support the will of the House,” Maloney said off the chamber floor after the vote. “They literally snatched discrimination out of the jaws of equality.”

“Our veterans and troops were prioritized over a political messaging amendment that could have jeopardized the final passage of the appropriations bill,” said Speaker Paul Ryan’s spokeswoman AshLee Strong in a statement.

The fracas highlights the risks for GOP leadership’s commitment to an “open amendment” process, where lawmakers are afforded wide latitude to offer changes to legislation, like the military construction and veterans affairs spending bill that was on the floor Thursday. Ryan, upon taking the gavel, vowed he would allow more amendments on the floor, but Thursday’s drama will surely test his commitment to that process.

It’s a good bet that other politically explosive issues will come up for votes if the Wisconsin Republican and his team continue the same practice through this summer’s spending bill process, so Ryan will have to determine whether the benefits outweigh the cost.

The acrimony undermined a success for Ryan earlier that day regarding his commitment to regular order. Just moments before the LGBT vote, he’d shepherded the first House vote to bar the Confederate flag from flying in mass graves at federal cemeteries.

The same amendment had tripped up Speaker John Boehner (R-Ohio) last year, and Boehner responded then by pulling an entire appropriations bill off the floor because he didn’t want to litigate the matter. He feared it would divide his conference and make it look bad following a high-profile racially charged shooting of black churchgoers in South Carolina.

On Thursday, however, GOP leaders were proud that they allowed the Democratic flag amendment on the floor. It passed 265-159, with all members of GOP leadership joining Democrats to back the measure.

But just moments later, things turned ugly during the LGBT vote.

When the votes began shifting out of the ‘aye’ column on Maloney’s measure, booing erupted in the chamber. Almost every Democrat was on his or her feet shouting and eventually they broke out in a chant, pointing their fingers at the other side of the chamber where the Republicans sit: “Shame! Shame! Shame!”

Rep. Joe Crowley (D-N.Y) framed his hands around his mouth like a megaphone and shouted something no one could hear over the din. Rep. Steve Israel (D-N.Y.) had his hands crossed and wore a sharp scowl. Rep. Rosa DeLauro raised her hands in the air during the chanting. Others paced, while some just stood in shock.

Republicans on the other side sat in their seats quietly. Some looked disappointed. As the amendment was being voted down, Rep. Ileana Ros-Lehtinen appeared to shake her head in disappointment. The Florida Republican has a transgender son and is one of the few Republicans who has been outspoken in advocating for the LGBT community.

After the chair closed the vote, Democrats continued shouting in anger.

“There will be order in this chamber,” the chair said.

“No there will not be!” yelled Rep. Gwen Moore (D-Wis.), who stood at the base of the podium. She pounded her fists on the table in front of her.

Hoyer silenced the chamber and called for a parliamentary inquiry to find out how people switched their votes on an amendment that, until just moments before, looked like it would pass. Under House rules, once the speaker asks, “Does anyone wish to change their vote?” lawmakers are supposed to go to the front of the podium to change their votes.

But the speaker, however, never said that phrase during the LGBT ballot, keeping the vote open for longer than the standard two-minute voting block.

Hoyer argued that Ryan was tossing chamber rules aside and said the people who changed their votes should have the courage to step forward.

“I was standing in the well. No one came, or no one had the courage to come into the well to change their vote,” he thundered. “Notwithstanding that, the vote just came changing. How is that possible?”

Hoyer also threatened on the floor that Democrats would figure out who switched their votes on the amendment: “We will know. We’re working on it right now,” Hoyer told reporters after the vote. His office released the names a few minutes later.

It was the second time in as many days that Maloney offered the proposal on the floor. The House rejected similar language last night during debate over the defense authorization bill.

“I’ve been the majority leader. I’ve been the whip,” Hoyer said on the floor after the vote as he blamed GOP leadership for pushing lawmakers to switch their votes. But he again hit the seven Republicans who changed their positions. “They will have themselves to look at tonight in the mirror and explain to themselves whether their first vote was a principled one.”

House Rules Chairman Pete Sessions (R-Texas) said some lawmakers may have switched their votes because they recognized that the issue had been settled the night before during the defense authorization debate.

Sessions also defended the GOP on the substance of the matter.

“I am a Republican,” he said. “We do not discriminate — we attempt to follow the law, and the gentleman knows that.”