Like the institution it reflects, the hearing room in the Hart Senate Office Building is a place of grandeur and formality. It also is a place designed for the modern age of American politics. It is a stage set for television.

Cut into the dark mahogany woodwork forming three of its four rectangular walls are nothing less than anchor booths similar to those at national political conventions and positions for TV cameras. In the center of the fourth wall, forming the backdrop to the curved hearing table where senators sit in solemn deliberation, are marble panels into which is placed, depending on one's taste, a seal that is either majestic or pretentious and spells out: "United States Senate."

There was little majesty about many long, unhappy faces in that room this week as senators grappled with their unpleasant business of sitting in ethical judgment on one of their own, Dave Durenberger (R-Minn.).

The task was mercifully short, a mere two days instead of a possible two or more weeks, and memorable for several reasons, primarily Durenberger's remarkable and personal statement in his own defense. Seldom has a politician in trouble expressed himself with such eloquence and in a manner that skirted the shoals upon which others have crashed. He was neither defensive nor maudlin, he avoided demagoguery and stonewalling and openly acknowledged his mistakes.

Whether it will be enough to spare him from being formally denounced -- or even expelled -- by his peers for ethical lapses is unresolved and not the issue here. At stake is something more important than one senator. At stake is the way this case symbolizes the decline of the Senate as an institution.

The cause is money.

Driven by the need to raise vast sums for campaigns in the media age and to shore up political bases at home, in large part due to its failure to enact genuine campaign finance-reform legislation, the Senate fails to function effectively. Its pace drags, action on significant bills founders and a sense of frustration is pervasive. A breakdown is approaching.

Only days before the Durenberger matter came before the public, Majority Leader George J. Mitchell (D-Maine) put into words what most Washington politicians rarely acknowledge publicly but virtually all acknowledge privately: The system isn't working.

"We simply have to complete action on this and other measures in the Senate," Mitchell told colleagues on the Senate floor in explaining why they should stay late to act on major bills. "Unfortunately, what is occurring is, what should take an hour takes a day, what should take a day takes a week and, as a result, the progress is painfully slow."

He added, with obvious frustration and betraying an edge of bitterness about failure to act: "I say to the members of the Senate, I think this dramatizes in a way that no words that I could otherwise speak, the difficulty of accomplishing anything in the Senate.

"Two years ago, we adopted a practice of having the Senate in session three weeks out of a month, one of each four weeks not in session. Many Americans do not understand why it is that we do not work four weeks a month like they do. Now in the three weeks a month that we do work, senators do not want to have votes on Mondays, and they do not want to have votes on Fridays.

"We have three weeks in the month in which we work, and in those three weeks we have three days of the week in which the Senate can vote.

"Throughout this period, it has been stated in writing and publicly repeated that the one day on which the Senate would be in session into the evening and voting would be Thursdays. Now we have reached the situation where we cannot vote on a Thursday. . . . It is intolerable that the Senate cannot function if one or a few senators have something else to do on one of the three days of the week of the three weeks of the month that the Senate is supposed to be in session and working. . . .

"We are in a situation where everything we attempt to bring up we are unable to proceed with, and I must say it is extremely, extremely difficult and discouraging under the circumstances."

What Mitchell didn't explain was the main reason that senators are not working on Mondays, Fridays and every fourth week. It is because they are out raising money on the taxpayers' time.

Mitchell asked his colleagues this question: "How do we ever proceed in any responsible manner?"

Answer: Clean up your own financial act. Then most ethical problems will take care of themselves.