Every member of the United States Senate swears an oath to “support and defend the Constitution of the United States against all enemies, foreign and domestic” and makes a commitment to “bear true faith and allegiance to the same.” After the House of Representatives impeached Donald Trump for the incitement of insurrection that resulted in the deadly January 6, 2021, attack on the Capitol of the United States, the duty of true faith and allegiance to the Constitution demanded that senators try and convict the 45th president for the high crimes he committed.

On Saturday, a bipartisan majority consisting of 57 senators—50 Democrats and seven Republicans—judged Trump to be guilty, embracing the conclusion of Representative Jamie Raskin, the Maryland Democrat who served as the lead House impeachment manager, that “Donald Trump committed a massive crime against our Constitution and our people and the worst violation of the presidential oath of office in the history of the United States of America. For this, he was impeached by the House of Representatives and he must be convicted by the United States Senate.” It was, Senate majority leader Chuck Schumer (D-N.Y.) noted, “the largest and most bipartisan vote of any presidential impeachment trial in American history.”

Yet 43 Republicans voted against finding Trump guilty, preventing the Senate from achieving the two-thirds majority needed to hold the most dangerous and destructive president in the country’s history to account for his seditious acts. Schumer labeled that choice a “vote of infamy.”

The 43 Republicans who abandoned their oaths of office in order to defend Trump failed the Constitution.

That was not, however, the only failure to show true faith and allegiance to the Constitution that occurred on Saturday.

With their decision to shut down an effort by House impeachment managers to call witnesses in the trial of Donald John Trump, senators of both parties chose political pragmatism over constitutional duty.

In so doing, they rejected an opportunity to make the impeachment trial everything it could have and should have been. They abandoned their responsibility to use every tool that was available to them to check and balance the imperial presidency—in the immediate trial of Trump for incitement of insurrection and in the broader battle to renew the role of the Congress as the preeminent branch in a system of shared powers.

“The decision not to call witnesses [was] indeed a victory for Trump,” said constitutional lawyer and presidential accountability advocate John Bonifaz, the co-author of the book, The Constitution Demands It: The Case for the Impeachment of Donald Trump. “It makes absolutely no sense.”

The question of whether witnesses might be called had hovered over the trial from before it opened. On February 4, Raskin asked Trump to testify. Trump refused. That quieted the discussion in the initial stages of the trial. But as the trial headed toward its conclusion, Representative Jaime Herrera Beutler (R-Wash.) reopened it. As CNN explained, “Herrera Beutler revealed details about an expletive-laced phone conversation between McCarthy and Trump on Jan. 6 as the Capitol riot was underway. In the call Trump is reported to have said the rioters cared more about the election results than McCarthy did.” The statement from the congresswoman provided critical support for the argument that Trump was guilty of “dereliction of duty”—one of the key charges contained in the article of impeachment that was approved by a bipartisan 232-197 vote in the House.

“You have to look at what he did during the insurrection to confirm where his mind was at,” Herrera Beutler, who voted with nine other House Republicans to impeach Trump, told CNN. “That line right there demonstrates to me that either he didn’t care, which is impeachable, because you cannot allow an attack on your soil, or he wanted it to happen and was OK with it, which makes me so angry.”

She was right about that, as she was when she said called on “patriots” to speak up about Trump’s high crimes.

Raskin responded appropriately on Saturday. He explained on behalf of the House managers that “we believe we have proven our case.” Yet, he went on, because Herrera Beutler’s statement represented “additional corroborating evidence” of Trump’s dereliction, “and because this is the proper time to do so under the resolution that the Senate adopted to set the rules for the trial, we would like the opportunity to subpoena Congresswoman Herrera regarding her communications with House minority leader Kevin McCarthy, and to subpoena her contemporaneous notes that she made, regarding what President Trump told Kevin McCarthy in the middle of the insurrection.”

Trump’s hapless lawyers were caught off-guard and responded with unfocused objections and a wild proposal to call hundreds of their own witnesses. The Senate voted 55-45 to allow witnesses. It was a bipartisan vote that infuriated Trump loyalists such as Senator Ron Johnson (R-Wis.). What mattered was that this Senate deliberation looked, for a moment, like it might become an actual trial.

That did not happen.

After more than an hour of heated negotiations involving Schumer and the always cynical Senate minority leader Mitch McConnell (R-Ky.), the prospect of calling witnesses was taken off the table. A “deal” was reached. The impeachment managers had wanted to depose Herrera Beutler. Instead, her statement would merely be inserted into the trial record. That was the end of it.

Democrats had a majority for calling witnesses. They could have done so in a smart and effective way. But they lacked the will to see the process through. There would be no deposition. No direct testimony. No witnesses.

“Democrats presented a cogent impeachment case with detailed evidence, won a bipartisan vote to add key witnesses, then backed down on witnesses—ending the trial early and stripping their own case of any eyewitness testimony,” explained veteran legal analyst and MSNBC host Ari Melber.

The window closed. The opportunity was lost.

That was convenient for Republican senators who were not interested in hearing evidence that might make their votes against conviction any more shameful in the eyes of the American people. It was also convenient for Democrats—in the Senate, the House, and the White House—who simply want to “get on with the business of governing.”

But it was inconvenient constitutionally. The founding document gives “the sole Power to try all Impeachments” to the Senate, and requires every senator to swear a second oath to “do impartial justice.” That, said Senator Jon Tester (D-Mont.), should be understood a “solemn obligation.” This obligation is not merely to consider the evidence that is presented but to assure that evidence is allowed to be considered—including evidence from witnesses with information that is clearly relevant to doing justice.

The senators who thwarted the effort to call witnesses failed the Constitution.

“While I appreciate all of the incredible work the House Impeachment Managers have done at this impeachment trial, this decision to withdraw from calling witnesses is outrageous. It completely undercuts all that they have said,” explained Bonifaz, who continued: “If our Constitution and our democracy is on the line with this trial (as we have rightly been told), then why rest solely on video, audio, news reports, and one stipulated statement? Trials require witnesses. Would witnesses have changed the outcome? We will now never know. But history will judge this decision to stop the full airing of evidence before the Senate and the American people on why Trump should be convicted for inciting this insurrection.”

Bonifaz was right. But the saddest assessment came from Nebraska Senator Ben Sasse. In a statement announcing his vote to convict, the Republican warned:

Congress is a weaker institution than the Founders intended, and it is likely to shrivel still smaller. A lot of Republicans talk about restoring Congress’ power from an already over-aggressive executive branch. Conservatives regularly denounce executive overreach—but we ought primarily to denounce legislative impotence. This trial is constitutional because the president abused his power while in office and the House of Representatives impeached him while he was still in office. If Congress cannot forcefully respond to an intimidation attack on Article I instigated by the head of Article II, our constitutional balance will be permanently tilted. A weak and timid Congress will increasingly submit to an emboldened and empowered presidency. That’s unacceptable. This institution needs to respect itself enough to tell the executive that some lines cannot be crossed.

The constitutional balance has been tilted in the wrong direction. The Republicans who voted not to convict share blame for that. But so, too, do Democrats who failed, when they had control of the Senate, to fully embrace their authority to try Donald Trump.