But the real drama — and the real blow to the House managers — came a few minutes after 3 p.m. on Friday. A staffer came walking through the press gallery handing out photocopies of a press release from Sen. Robert Byrd, D-W.Va., and warned us not to rush out of the gallery as soon as we read it. This got a chuckle — such press releases rarely merit reading, let alone reporting — but it turned out to be a big deal. Byrd was announcing that he’d be voting to dismiss the charges against the president. Soon the same press release was making its way around the Senate floor.

Byrd has been the most overwatched Senator in the entire impeachment trial. Earlier in the month, he had pundits swooning when he condemned the president’s post-impeachment “rally” as an example of “shameless arrogance.” But Byrd is important because everyone has such an outsized impression of him. And he is known to hold the president, personally, in deep disdain. He had conspicuously held open the possibility that he could be persuaded to vote to convict Clinton. Every possible scenario for the president’s conviction required that Byrd vote to convict, and bring along a dozen of his Democratic brethren by sheer dint of his leadership. When Byrd announced he’d vote to dismiss the charges, it meant that not one Democrat would break ranks; and the Republicans knew it.

Byrd’s announcement left the managers, and a lot of Republican senators, really pissed off. I saw Rep. James Rogan coming down one of the stairwells with a gaggle of reporters, griping about Byrd and asking why he couldn’t have waited at least until the day’s presentations were over. Clearly, Byrd’s announcement crystallized the steady erosion of support for a full-length Senate trial.

But it only confirmed a more pervasive shift in the mood of the proceedings: They had become a distinct embarrassment to the Senate, especially to Republicans. Later that evening one Republican insider told me how a number of the marquee “moderate Republicans” from last month’s House impeachment fight had called him and told him they never would have voted to impeach if they had known it would come to this. Sen. Orrin Hatch, R-Utah, was proposing that the trial merely be adjourned with the Senate voting to “acknowledge” the House’s vote to impeach the president. By the evening, it seemed clear that the only question left wasn’t whether the trial would end, but how it could be ended with everyone allowed to save face.

But the House managers came back on Saturday with a bold new sortie: They had gotten independent counsel Kenneth Starr to invoke her immunity agreement in order to compel Monica Lewinsky to be interviewed by them. (More than one pundit called it a Hail Mary pass.) In private, of course, Democrats concede that they’re quick to depict Republican moves as partisan or shady. But the attempt to bring in Starr to lean on Lewinsky, just as the possibility of witnesses seemed to be fading, caused genuine surprise and even some real outrage on the part of Senate Democrats. Senators who had kept their comments measured and cool let go with words reminiscent of last year’s fight in the House.

On Saturday, Tom Daschle told Salon, “They don’t get it. They can’t help themselves. They have so much venomous hatred towards the president that they’re on this path of self-destruction that will lead them ultimately, I think, to an extraordinary demise.” Daschle’s comments echo a frustration that is heard often on the Democratic side of the aisle. With polls showing the Republicans taking a terrible beating for prolonging the impeachment trial, Democrats are thinking to themselves: How long and how hard do we have to beg them not to adopt a course that will do them immense political damage?

Of course, some Senate Republicans are looking for a way out. Sen. Trent Lott had floated a proposal to skip over the divisive motions to dismiss and to call witnesses, in order to cut straight to a vote on the two articles of impeachment, but he was attacked by his own caucus. On Monday Lott decided to take a different tack, joining with nine other Republican senators to send Clinton 10 questions about the matters at hand, but no one was expecting the president to reply.

Lott also made it clear that the Republicans had the votes to defeat the Byrd motion to dismiss, and that they intended to do so. “We have the votes, I believe, not to dismiss it at this point,” Lott told the Associated Press Monday. “I think that is a short-circuiting of the process that would not be fair. The American people would not agree with that.” (Actually, given the state of the public opinion polls, if the Democrats could get Lott to say that under oath, they could probably get him for perjury.)

By Monday morning, it was clear that efforts to reach a compromise that would let the Senate forego both a vote on dismissal and on witnesses had failed. The Senate took up Byrd’s resolution to dismiss the charges against the president and bring the trial to a halt. White House lawyers and House managers made their respective cases for and against the resolution; but even while they were doing so, attention was shifting toward the upcoming vote on whether to depose witnesses — the decision that is quickly shaping up to be the decisive vote of the trial. Over the weekend, four to six Senate Republicans indicated they would vote against calling witnesses; Democrats only need a half-dozen defections to put that issue behind them.

Monday ended with a vote, not on the resolution to dismiss, but on whether to set aside the Senate impeachment rules dictating that deliberations be held in closed sessions. After this resolution went down, 57-43, the Senate reconvened in executive session to debate Byrd’s motion to dismiss the charges.

The behind-closed-doors discussion was appropriate, symbolically at least, because that’s where all meaningful discussions about how to end the trial are now taking place. There is still a possibility that the trial could conclude by the week’s end. But this scandal has always moved by its own distinct logic. As the pressures inside the Republican camp grow more intense, expect a long week of confusing, erratic decisions on both sides of the aisle, with more plot twists to come.