WASHINGTON -- Republicans in the U.S. Senate on Friday derailed a bipartisan inquiry into the deadly assault on the Capitol by former President Donald Trump's supporters, despite a torrent of criticism they were playing down the violence.

Democrats and some moderate Republicans had called for a commission to probe the events leading up to and on Jan. 6, when hundreds of supporters of Trump, a Republican, stormed the Capitol, fighting with police, urging violence against lawmakers and delaying the formal certification of President Joe Biden's election victory. The violence left five people dead including a Capitol Police officer.

The measure failed by a vote of 54 to 35, short of the 60 votes needed to advance the legislation in the 100-member Senate. The 35 no votes were all Republicans.

"We all know what's going on here. Senate Republicans chose to defend the Big Lie because they feared that anything that might upset Donald Trump could hurt them politically," Senate Democratic Leader Chuck Schumer said after the vote.

It was the first time this year that Republicans were able to use the 60-vote hurdle, known as a filibuster, to defeat legislation.

The vote underscores the steep challenges for Democrats in the evenly divided chamber, as they will have to win at least some Republican support in order to pass policing reforms, voting-rights legislation and other priorities.

Senate Republican Leader Mitch McConnell has argued that the Capitol attack commission would duplicate work done by other congressional committees, as well as a sweeping federal criminal investigation that has so far has resulted in the arrests of more than 440 people.

But Republicans are also concerned that the commission, modeled on one that probed the Sept. 11, 2001, attacks, would focus attention on the violence and on Trump's persistent false claims about the 2020 election well into next year's midterm congressional election campaigns.

The proposal already passed the House of Representatives with the support of all Democrats and one in six Republicans.

"We just can't pretend that nothing bad happened, or that people just got too excitable. Something bad happened. And it's important to lay that out," Senator Lisa Murkowski, one of six Republicans who supported the measure, told reporters late on Thursday.