In many ways he is a classic case for a textbook on civics and government or, if you hoke it up a little, for a Washington novel.

He wields considerable power in Washington and, impeccably turned out in a three-piece pin stripe suit, he looks it. He has an encyclopedic knowledge of the nitty-gritty of the government's workings and will be a central player in the most controversial legislation enacted by the Congress in years, the Gramm-Rudman-Hollings deficit-reduction law.

But it's unlikely that one in 1,000 on the streets of the capital recognize him as he walks by. He is the quintessential faceless bureaucrat.

He is Charles A. Bowsher, the comptroller general of the United States and head of the General Accounting Office. And some time next September he will have his moment in the spotlight. He will be the auditor who determines whether Congress and President Reagan have managed to cut the federal budget deficit down to $144 billion as Gramm-Rudman-Hollings requires for fiscal 1987 or if the automatic across-the-board budget cuts for many programs -- "sequestration" -- must go into effect.

If the GAO audit determines that the target figure hasn't been met, the sequestration could set off the biggest uproar in this city since Watergate or the days of the late Sen. Joseph R. McCarthy (R-Wis.). The speculation around his office and on Capitol Hill is that the arbitrary cuts might have to be as much as $30 billion to $50 billion -- enough to send, figuratively speaking, blood running through the corridors of the Capitol.

"People wanted tough medicine when they passed Gramm-Rudman, and I think it might take good tough medicine to get the process started," Bowsher said in an interview. "I don't think it would be good over the full five years [that the law is supposed to remain in force], but if it can force some compromises on budget cuts and revenue enhancements, it could be a good thing."

In August, the Office of Management and Budget and the Congressional Budget Office each will take a "snapshot" of the federal budget to see if the deficit is going to meet the target figure of $144 billion. If it's within $10 billion of the mark, the president and Congress will have to work out cuts to get it in line. If it's more than $10 billion over, the across-the-board cuts will go into effect.

The GAO's function is to audit the OMB and CBO figures for accuracy and force them to take another look at the budget if the numbers seem out of line. Bowsher's role is being challenged both on constitutional grounds and because, some critics say, the GAO is understaffed and incapable of producing the accurate and fast audit (about six days) required.

Bowsher laughed off the charges.

"Our function in Gramm-Rudman is one of audit and review, which is our overall role," he said. "We brought in outside consultants in two areas, economic forecasting -- the president of Chase Econometrics and Bruce MacLaury of the Brookings Institute, for instance -- and in defense. We need them to check out our thinking on how much obligational authority we need to take away to make the cuts."

The constitutional challenge to the comptroller general's role is raised in a lawsuit filed by Rep. Mike Synar (D-Okla.) and several other members of Congress. They contend that the comptroller general's role in Gramm-Rudman-Hollings is unconstitutional because the intent of Congress in creating the office was that he be a legislative officer and not an independent official of the United States. Therefore, they argue, he is not legally empowered to perform the executive function assigned him by the new law.

Bowsher disputes this view. "The intent of Congress [when it founded the GAO in 1921]. . . was to give the office an element of independence," Bowsher said. "We had a similar challenge last year on a competition in contracting ruling. We've been upheld in a federal court, and it's now in appeals court."

Bowsher, 54, was nominated by Reagan and confirmed in October 1981. A graduate of the University of Illinois and the University of Chicago Graduate School of Business, he is a certified public accountant and was a partner with Arthur Andersen and Co., a major national accounting firm, for 25 years.

He served four years as assistant secretary of the Navy for financial management in the Johnson and Nixon administrations. He was involved in several recent major fiscal crises -- Lockheed, Penn Central and the U.S. government bailouts of New York City and the Chrysler Corp.

The GAO employs about 5,000 people, half in Washington, the other half in 15 regional offices around the nation plus branch offices in Honolulu, Frankfurt, West Germany, and Panama City, Panama.

It audits nearly all the activities of the federal government, from the MX missile and the B1 bomber to Social Security and the Internal Revenue Service. The GAO has issued about 2,500 reports on various government programs during Bowsher's tenure. It issues a large number of nonbinding recommendations to Congress for program changes, about 60 percent of which are accepted, Bowsher said.

It also makes legal rulings, which are binding. One was that then-Secretary of the Interior James G. Watt had to reimburse the government for the coast of his Christmas party at Arlington National Cemetery. Another was that the Defense Department had improperly used operational and maintenance funds for training in Honduras.

Bowsher has also initiated management reviews of several Cabinet departments and federal agencies, including the departments of Justice, Labor, Housing and Urban Development, and Transportation and the Defense Logistics Agency. One of his problems is that there are more than 400 accounting systems in the federal government, none of which are computer-compatible with each other and most of which serve different figures on the same programs.

"Gramm-Rudman is reminding us of the poor quality of accounting in the government," he said. "Some systems are not in very good shape, and many don't tell us if we're really making good decisions on cutting programs. We're running a trillion-dollar operation with a World War II accounting system, and it doesn't make sense."