The impeachment trial of President Donald Trump began Thursday when John Roberts, chief justice of the Supreme Court, directed all of the senators to stand and raise their right hands. Ever since, I can’t get two questions out of my head.

The first: How in God’s name — and it was in God’s name — can the Republicans who have already decided to acquit Trump take a solemn oath to administer “impartial justice”? They’re partial to the core, unabashedly so, as their united march toward a foregone conclusion shows. A mind meld this ironclad isn’t a reflection of facts. It’s a triumph of factionalism.

The majority of the party’s senators have said outright or clearly signaled that they have no intention of finding the president guilty and removing him from office. Yapping lap dogs like Lindsey Graham and obedient manservants like Mitch McConnell have gone further, mocking the whole impeachment process.

So the oath they took: How does that work? Did they cross the fingers on their left hands? Do they reason that U.S. politics has reached a nadir of such fundamental hypocrisy and overweening partisanship that no one regards that pledge as anything but window dressing?

Certainly they’re telling themselves that their own political survival, hinging on obsequiousness to a president with a talent for retribution, matters more than honor. Over the three years of the Trump presidency, they’ve become expert at that calculation.

My second question is really a subset, corollary or anagram of the first: How can Marco Rubio, Ted Cruz and Martha McSally stand to look at themselves in the mirror? I’m singling out these three somewhat randomly but also because they’ve traveled particularly self-mortifying journeys away from self-respect.

At a news conference Thursday afternoon, Chuck Schumer, leader of the Senate’s Democratic minority, said that when the chief justice walked into the chamber earlier that day, “I saw members on both sides of the aisle visibly gulp.” Schumer attributed that to the palpable “weight of history.” But for many of them, it probably had more to do with their awareness that they were about to sell out again, this time in circumstances that would be remembered long into the future.

Democrats, too, have made up their minds, and that would be equally upsetting but for the mountain of actual evidence on which their judgment rests. You can erase all the testimony in the House by Gordon Sondland, David Holmes, Alexander Vindman, Fiona Hill and others. You can delete Mick Mulvaney’s admission at a White House news conference of a quid pro quo. You can discount Lev Parnas’ ongoing aria of atonement. Still, you have the transcript (of sorts) of Trump’s “perfect” phone call with the president of Ukraine, in which it’s clear to any sane reader with a semblance of common sense that he’s trying to trade U.S. aid for the smearing of Joe Biden.

If there were nothing to this, why would Trump stonewall Congress to the extent that he has? That’s not how the innocent act.

When witness after witness tells a version of the same story, providing pieces of a puzzle that fit snugly together, you can reach a conclusion about the whole of it. That’s called logic.

And if the actual case against Trump were weak, why would Republicans keep redirecting attention to Democrats’ motivations — to how much they despise the president? That’s called distraction.

McSally practiced it Thursday when, in a moment of breathtaking hostility, she answered a reasonable question from Manu Raju of CNN about whether any new evidence should be presented during the Senate trial by snarling, “Liberal hack!”

She’s terrified. Her state, Arizona, is increasingly purple. She lost her 2018 race for the Senate and ended up in the chamber only by appointment following John McCain’s death. She has to run again this year, against Mark Kelly, the former astronaut, who’s a popular figure. She’s vulnerable, and standing with Trump is almost as much of a gamble as standing up to him would be.

But she once did stand up to him. She used to have guts. Before going into politics, she blazed trails as an Air Force pilot and even sued the secretary of defense when she detected discrimination against women. During her successful campaign for the House in 2016, she pointedly didn’t endorse Trump and just as pointedly spoke out against the behavior that he copped to — no, bragged about — in that infamous “Access Hollywood” tape. McSally had a moral compass then.

Now she just has a hunger to hold onto her suite of offices in the Capitol. She has wagered that emulating Trump is her best bet. At the conclusion of this pathetic excuse for a trial, she’ll vote to acquit him — impartially, of course.

She’ll be joined by Cruz and Rubio, who are special targets of my disappointment because they were once special targets of Trump’s ugliness. They know it firsthand and well.

They campaigned against him for the Republican presidential nomination in 2016, when he didn’t just criticize them but viciously belittled and even savaged them. He conspiracy-theorized a role for Cruz’s father in John F. Kennedy’s assassination.

“A pathological liar,” Cruz called Trump.

But now that Trump is president and his base has become the most impassioned constituency in the party, Cruz is his biggest cheerleader and a ready mouthpiece for all of those lies. He has swapped thoughts of 2016 for thoughts of 2024, when there’s another opportunity to reach for the White House and Trump’s loyalists will come in handy. He’ll have to muscle aside Javanka and Don Jr., but that’s a pickle for another day. First step: acquittal!

Rubio has long fashioned himself a foreign-policy maven and took a hard line when it came to Russia. So you might think that the Trump presidency would be especially galling to him. You might also think that Trump’s bullying of Ukraine — which left the country more vulnerable to Russian aggression — would be some sort of breaking point.

But he’s a Republican member of Congress in 2020, which means he’s a sycophantic shell of his former self. And having bitten his tongue about Trump’s global misadventures, he’ll now abet more of the same by helping Trump stay in office.

There are so many other Republican senators to marvel at. Mitt Romney, what was the point of diving back into public life if you’re going to prop up a president whose fraudulence you once gave a whole long speech about? Lamar Alexander, you venerated Howard Baker, a fellow Tennessean who once held your Senate seat and put principle above partisanship by standing up to President Richard Nixon. Why not do the same and stand up to Trump?

Susan Collins, I can’t imagine the exhaustion of your role as political wild card, scrutinized to a fare-thee-well. But come on. If you’re going to pride yourself on autonomy, you need to exercise it when it matters most.

It’s not fun to be any of you right now, with McConnell above you and #MAGA hellions below you poised to make your life a misery if you stray. But no one forced you into public service. When you entered the Senate, you took an oath, and you took another one Thursday. I have a third question, maybe just a rewording of the first and second: Doesn’t that nag at you even a little?

Frank Bruni (CREDIT: Earl Wilson/The New York Times)

Frank Bruni is an Op-Ed columnist for The New York Times.