U.S. Rep. Conor Lamb is known for a willingness to work across the aisle.

But after a mob stormed the Capitol last week and 139 House Republicans still voted to overturn the results of the presidential election, the moderate Democrat from Southwestern Pennsylvania said he’s not sure he can stomach working with those lawmakers again.

“It’s going to be very difficult to reason with them,” said Lamb, who regularly prayed with several of the Republicans who pushed President Donald Trump’s false claims of a stolen election and even worked on infrastructure legislation with one of them.

“Some of these Republican members are just refusing to see the connection between their own words and what the mob did when it attacked, even though the connection is plain as day,” Lamb said in an interview before the House voted Wednesday to impeach Trump for his role in inciting the attack. “They’ve become morally blind to the consequences of their own actions.”

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Lamb has cut a moderate profile in a competitive district, twice voting against Nancy Pelosi as House speaker and pledging to work with Republicans. But last week, as debate on certifying Pennsylvania’s Electoral College votes stretched into early Thursday morning, he tussled with Republicans on the House floor.

“We know that that attack today, it didn’t materialize out of nowhere, it was inspired by lies, the same lies that you’re hearing in this room tonight,” Lamb said then. “And the members who are repeating those lies should be ashamed of themselves, their constituents should be ashamed of them.”

Republicans objected to his use of the word “lies,” and a pair of lawmakers briefly appeared near blows.

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Lamb this week dismissed Republicans who argue that impeaching Trump a second time in the closing days of his term will only further divide the country.

“Every second Donald Trump holds the power of the presidency is a second in which he can hurt our communities or our governing institutions themselves,” Lamb said. “It’s hard to come to grips with the fact that our president incited an armed attack on another branch of government just last week, but he did, and we must act.”

Lamb wasn’t in the Capitol during the attack because of pandemic precautions that limit the number of lawmakers allowed on the House floor. He watched the insurrection unfold the same way much of the country did — on live television.

“I felt horrified, angry, and concerned for my colleagues,” Lamb said. “The No. 1 thing that haunts me is the sight of the Trump and Confederate flags flying in and on the Capitol. Foreign flags flying at the Capitol. That’s an invasion.”

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Lamb conceded that an impeachment trial will distract from President-elect Joe Biden’s agenda in the earliest days of his administration, but said the Senate should be able to simultaneously manage a trial and vet Biden’s cabinet nominations. He likened members of Congress to “essential workers” and said it’s time for him and his colleagues to start working overtime the way health care workers have since the beginning of the pandemic.

“There’s a lot to do to protect and shore up this democracy,” Lamb said. “This is the first step.”

He’s not sure what will come of the prayer group he shared with several Republicans who voted to overturn the election once Biden is inaugurated.

“There are personal relationships at stake, personal relationships I worked hard to build,” Lamb said. “I hope to still participate. Prayer could be the best way to repair the breach.”