“This is not the Senate I came to 24 years ago,” he lamented. “This blanket of comity and respect is pretty threadbare right now.”

In some ways, the legislative dynamic was a reverse of the situation 12 years ago when the House, in fits of acrimony and blame, got tied in knots over the 2008 economic rescue and left it to the Senate to more calmly go about its business despite deep divisions of its own. This time, it was the Senate that became bogged down in fighting while the House seemed more grown up — something no self-respecting senator ever wants to contemplate.

Perhaps the most troubling aspect of the toxic spectacle that unfolded on the floor was how manufactured all the outrage appeared to be. Negotiations were continuing just steps away in the leadership offices of both Republicans and Democrats, and virtually everyone knew that there was going to be a resolution at some point soon — though majority Republicans were up in arms that Democrats were using their leverage to extract more of what they wanted. The harsh attacks — and the Republican suggestion that Democrats were pushing extraneous provisions that really were not part of the relevant negotiations — were in some ways pure political theater.

“Frankly, I think what has been happening on the floor today has been sort of artificial and hasn’t really shown the American public what is truly going on,” Senator Tim Kaine, Democrat of Virginia, said in a speech on Monday. “There were a lot of speeches that were taking place wherein it was sort of a blame game, and I don’t think that is what Americans wanted to see today.”

“What Americans didn’t see yesterday and today is the intense dialogue and debate and discussion around the third coronavirus response bill — by far the largest,” Mr. Kaine said.

One reason for the furious show of partisanship was obvious: Senators are engaged in a fierce battle for control of the chamber in November. Several Republican incumbents are in serious trouble and were not going to miss the opportunity to try to score points against Democrats for irresponsibility and to show voters back home they were fighting the good fight in Washington. With Senator Chuck Schumer of the New York, the Democratic leader, organizing the campaign against them, Republicans were particularly agitated when discussing him. Mr. Schumer, who was at the center of the negotiations, drives Republicans into a frenzy.

“People are dying, and the Democratic leaders think it an opportunity to score political points and grab power,” said Senator Martha McSally, a highly endangered Republican from Arizona, who took the floor to accuse Mr. Schumer of “flat-out lies.”