Washington ? One remarkable feature of the pending Senate showdown over the Democrats’ use of threatened filibusters to block the confirmation of some of President Bush’s judicial appointments is the virtual invisibility of those at the center of the controversy.

According to the Administrative Office of the U.S. Courts, there are 163 sitting active appeals court judges and 16 vacancies. Those judges have to be among the least known of all significant federal officials.

It is doubtful that one American in 100 can name a single such judge. They are scattered through 13 circuits and they sit, not individually, but in panels of three or more, rendering collective judgments on cases appealed from the district courts.

President Bush has had 35 circuit judges confirmed, but the Democrats’ use of the filibuster threat to block 10 others has brought the White House and the Republican Senate leadership to consider seriously changing the rules and ending unlimited debate on judicial nominees. That would reduce the number required for approval from 60 votes to 51.

How, one must ask, could figures so anonymous become the leverage points for such a historic and radical institutional change? The whole concept of the Senate — as distinguished from the House — was a place where minority interests and views would be balanced against those of the prevailing majority. One would think it would take a monumentally important issue — something larger than the identity of 10 among 179 largely anonymous officials — to occasion such a revolutionary change.

One theory is that the fight over the 10 blocked circuit judges is a sham battle, just an excuse the Republicans are using so they can later confirm a Bush Supreme Court nominee by that simple majority. I am not that cynical, and having interviewed antagonists on both sides of the circuit fights, I think their anger and frustration are real.

Two other factors are more plausible. It is a historical fact that the circuit courts have produced many Supreme Court justices, and all six of the appointments in the past 20 years have come by that route. So if one of the nominees is seen as a potential justice, you could understand the fervor to advance or block him or her.

But the more important reason, I suspect, is that the interest groups that have mobilized over the judiciary find it very useful to broaden the battleground beyond the Supreme Court.

Fighting over judges has become a highly profitable cottage industry in Washington. It goes back at least to President Reagan’s failed appointment of Judge Robert Bork to the Supreme Court — opposed by a huge liberal coalition and supported ardently by conservatives. Almost every subsequent Supreme Court vacancy has seen an increase in interest group lobbying — first of the White House and then of the Senate.

But Supreme Court vacancies are sporadic; none has occurred since 1994. To maintain their supporters’ interest — and the flow of contributions that finance their staffs — the interest groups need more fights. And that is what the regular turnover in the ranks of the circuit courts provides.

It matters not to these groups how much or how little the broad public knows of the records and personalities of these appointees. As long as activists can be convinced they are threats to the system — or martyrs — that will suffice.

But it is remarkable that the United States Senate is considering reducing itself to a smaller version of the House of Representatives by curtailing its long tradition of unlimited debate, merely to satisfy the imperatives of rival interest groups.

And it is not too late for cool reason to prevent this from happening.

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My column of April 7 quoted authors Dean Baker and David Rosnick as saying that the Congressional Budget Office calculated that an increase of 0.7 percentage points in Social Security taxes would make the system solvent for the next 75 years. That estimate, they now acknowledge, was, in fact, one Baker and Rosnick developed themselves, using CBO estimates for 50 and 100 years. CBO says the correct figure for 75 years is 1.04 percent.

My column of April 10 said that when the House Financial Services Committee held its hearing on the controversial administration proposal to shift the $4.7 billion Community Development Block Grant from the Housing and Urban Development Department to the Commerce Department, one scheduled witness, Clay Johnson, a deputy director of the White House Office of Management and Budget, “submitted a statement and did not show up.” The committee has informed me that Johnson was present for the hearing but, with dwindling attendance and votes coming up on the floor, was never called on to testify. I am happy to set the record straight.

— David Broder is a columnist for Washington Post Writers Group.