Senate Republicans have blocked the creation of a special commission to study the deadly 6 January attack on the Capitol, dashing hopes for a bipartisan panel amid a Republican push to put the violent insurrection by Donald Trump’s supporters behind them. Republicans killed the effort to set up a 9/11-style inquiry into the attack on the Capitol by a pro-Trump mob despite broad popular support for such an investigation and pleas from the family of a Capitol police officer who collapsed and died after the siege and other officers who battled the rioters. In a procedural vote in the Senate on Friday, six Republican senators broke ranks to back the commission, which was more than expected, but four fewer than the 10 needed to overcome a filibuster and for it to advance. The Senate majority leader, Chuck Schumer, condemned Republican colleagues for blocking a bipartisan commission. “Shame on the Republican party for trying to sweep the horrors of that day under the rug because they’re afraid of Donald Trump,” Schumer said in a Senate floor speech immediately after the vote. The House speaker, Nancy Pelosi, meanwhile, argued the vote on the commission bill brought “shame” to the Senate and would make the country less safe. She indicated that House committees, which are under Democratic leadership, would continue to investigate the attack. “Democrats will proceed to find the truth,” Pelosi said. The insurrection was the worst attack on the Capitol in 200 years and interrupted the certification of Joe Biden’s win over Trump. But the Republican party remains firmly in the grip of Trump who had made his opposition to the commission very clear. Observers believe that senior party figures do not want to anger the former president or his legion of supporters and may also fear what the commission might uncover in terms of links between some of the rioters and Republican lawmakers. Though the commission bill passed the House earlier this month with the support of almost three dozen Republicans, Republican senators said they believe the commission would eventually be used against them politically. Trump has called it a “Democrat trap”. While initially saying he was open to the idea of the commission, the Senate Republican leader, Mitch McConnell, turned firmly against it in recent days. He has said he believes the panel’s investigation would be partisan despite the even split among party members. McConnell, who once said Trump was responsible for provoking the mob attack on the Capitol, said of Democrats: “They’d like to continue to litigate the former president, into the future.” The Republican opposition to the bipartisan panel has revived Democratic pressure to do away with the filibuster, a time-honored Senate tradition that requires a vote by 60 of the 100 senators to cut off debate and advance a bill. With the Senate evenly split 50-50, Democrats needed the support of 10 Republicans to move to the commission bill, because Republicans invoked the filibuster. The episode has sparked fresh debate over whether the time has come to change the rules and lower the threshold to 51 votes to take up legislation. On Friday, the Democrats only got 54 votes by the time the vote was gaveled out. Friday’s vote marked Senate Republicans’ first official use of the filibuster to defeat a bill, and Schumer said he hoped this was not the beginning of a trend of Republicans blocking “reasonable, commonsense legislation”. The six Republicans who voted for the commission to proceed were Bill Cassidy of Louisiana, Susan Collins of Maine, Mitt Romney of Utah, Lisa Murkowski of Alaska, Ben Sasse of Nebraska and Rob Portman of Ohio. A spokesperson for the Republican senator Pat Toomey told HuffPost that he was not in Washington for the commission bill vote because of a family obligation However, the spokesperson said, Toomey would have voted in favor of starting debate on the bill. Senator Elizabeth Warren said on Twitter: “If Senate Republicans can block an independent commission investigating a deadly armed attack on the Capitol because it might hurt their poll numbers with insurrectionists, then something is badly wrong with the Senate. We must get rid of the filibuster to protect our democracy.” The Republicans’ political arguments over the violent siege – which is still raw for many in the Capitol, almost five months later – have frustrated not only Democrats but also those who fought off the rioters. Michael Fanone, a Metropolitan police department officer who responded to the attack, said between meetings with Republican senators that a commission is “necessary for us to heal as a nation from the trauma that we all experienced that day”. Fanone has described being dragged down the Capitol steps by rioters who shocked him with a stun gun and beat him. “So I don’t understand why they would resist getting to the bottom of what happened that day and fully understanding how to prevent it. Just boggles my mind,” she said. Video of the rioting shows two men spraying Sicknick and another officer with a chemical, but the Washington medical examiner said he suffered a stroke and died from natural causes.