FILE - In this Jan. 6, 2021 file photo, rioters climb the west wall of the the U.S. Capitol in Washington. First, some blamed the deadly Jan. 6 attack on the Capitol on left-wing Antifa antagonists, a theory quickly debunked. Then came comparisons of the rioters as peaceful protesters, or even “tourists." Now, Trump allies rallying in support of those people charged in the Capitol riot are calling them “political prisoners," a stunning effort to revise the narrative of that deadly day. (AP Photo/Jose Luis Magana, File)

Framing his diplomatic visit to Europe within a broader historical mission, President Joe Biden warns us authoritarians are eager for democracy to fail. He knows democracy’s enemies are active. He must act to fully expose the most overt assault on our system of self-government since the Nixon era.

Congressional Democrats should move swiftly to establish a select committee to investigate the Jan. 6 insurrection.

Like many Americans, the president expressed his preference for an independent bipartisan commission to conduct that investigation. But that path was closed last month when Senate Republicans killed the Jan. 6 commission bill. They did so at the bidding of Donald Trump and of Senate Minority Leader Mitch McConnell, who articulated one of their more absurd arguments against the commission.

“I think we will know everything we need to know. We were all witnesses,” he said. “We were right there when it happened and I simply think the commission is not necessary.” When a shattering crime occurs and a major witness then insists that an investigation is “not necessary,” suspicion immediately arises concerning that person’s consciousness of guilt. McConnell has aimed to prevent or discredit an investigation of Jan. 6 not because we “know everything we need to know,” but because he’s scared to death of what we will learn. On Trump’s orders, the minority leader instructed his caucus to vote down the commission, its pre-midterm deadline and a host of other features demanded by House Republicans.

This isn’t the first time Republicans have tried to evade scrutiny of a catastrophe for which they were culpable. The bill establishing a commission to investigate Jan. 6 was modeled on the 9/11 Commission — but that probe was nearly killed by aides to President George W. Bush, who feared he would be blamed for failing to curtail the al-Qaida plot. Then-Vice President Dick Cheney made a threatening phone call in the spring of 2002 to Sen. Tom Daschle, the Democratic majority leader, warning any investigation of 9/11 would be seen as a partisan maneuver and a hindrance to the “war on terror.” Cheney’s intervention is ironic in hindsight since his daughter Liz is among the handful of Republicans who urge a thorough investigation of the Capitol insurrection.

Congress ignored Cheney’s whining; Bush reluctantly signed the enabling legislation; and the 9/11 Commission discharged its duties, issuing a report that escaped the “partisan” taint. The Republicans have only themselves to blame for shutting down the option of a commission on which they would have shared equal authority with Democrats. House Speaker Nancy Pelosi should create a select committee to investigate. With House Republicans behaving as if nothing untoward happened, the select committee ought to operate with a Democratic majority and a tough chair who will dismiss obstruction and distraction from the minority. And unlike the commission Republicans stupidly killed, it would have the power to issue subpoenas without their consent. Some Democrats in Congress fear any investigation of Jan. 6 will suffer from accusations of partisanship. Minority Leader Kevin McCarthy has already leveled that charge against the bipartisan commission. Republicans are never more indignant than when they’re faking it. But who cares what McCarthy thinks anyway? What will matter in the investigation of Jan. 6 is an undaunted finding of facts. It is possible such an investigation will benefit Democrats in the midterm elections and beyond. That’s why Republicans want to stop it at all costs.

Too bad for them. Unearthing the truth about a violent assault on our Constitutional procedures — nothing less than an attempted coup d’etat — is a fundamental duty of Congress that cannot be evaded. Tempted by authoritarianism, the Republicans have chosen to dishonor their oath and cover up a crime against our country. There must be consequences for that, or we will forfeit our democratic heritage, perhaps forever.

Joe Conason is a nationally syndicated author.