WASHINGTON — House Republican Leader Kevin McCarthy said Tuesday that he won't support a proposal to form an independent, bipartisan commission to study the deadly Jan. 6 insurrection at the U.S. Capitol, almost certainly eroding GOP support ahead of a vote and positioning his party as opposed to investigations of the attack. 

McCarthy said he wanted the new panel to look beyond the violent uprising by supporters loyal to Donald Trump, who were trying to stop the certification of President Joe Biden's election. McCarthy pushed to have the new commission also investigate other groups, namely the Black Lives Matter groups that protested police violence in the aftermath of the death of George Floyd. 

He said that given the "shortsighted scope that does not examine interrelated forms of political violence in America, I cannot support this legislation."

McCarthy's opposition all but ensures this week's vote will have less Republican support in the House, and dims its chances in the evenly divided Senate — threatening the bipartisan commission's chances as Democrats say it is essential to reckoning with the violent attack that interrupted electoral count. 

The GOP leader's dissent comes as some other Republicans have started to downplay the severity of the attack, further aligning themselves with Trump. At a House hearing last week investigating the siege, one member denied there was an insurrection at all while another said a woman who was shot and killed by police while trying to break into the House chamber was "executed." Many other Republicans have tried to change the subject, saying Democrats should focus on the violence in cities instead. 

And it comes as some have suggested McCarthy himself could be subpoenaed by the panel because he talked to Trump as the insurrection was happening. Wyoming Rep. Liz Cheney, who was booted out of GOP leadership last week for her criticism of Trump's lies about the election being stolen, suggested as much in an interview with ABC News, saying she "wouldn't be surprised" if McCarthy was investigated as part of the probe. Cheney has supported the commission. 

Another Republican backing the bill is New York Rep. John Katko, who negotiated it with Democrats as the top GOP member of the House Homeland Security Committee. The bill does not suggest the commission investigate the riots in the aftermath of Floyd's death, as Katko's colleagues had suggested, but it does create a panel that is evenly split between Republicans and Democrats and gives them equal subpoena power — a change from House Speaker Nancy Pelosi's original proposal, which had more Democrats sitting on the commission and weighted subpoena power. 

Like Cheney, Katko was one of 10 Republicans who voted to impeach Trump after the insurrection for telling his supporters that day to "fight like hell" to overturn his defeat. The Senate later acquitted him. 

Modeled after the investigation into the 9/11 terrorist attacks, the bill would establish an independent 10-member commission that would make recommendations for preventing another insurrection. The panel would have to issue a final report by Dec. 31. 

The bill's path forward is uncertain in the 50-50 Senate, where Republicans have been quiet on the commission in recent weeks and several have said they don't think it's needed. Senate Republican Leader Mitch McConnell objected to the initial proposal by Pelosi, saying it should also investigate last summer's riots.