Here now another vignette from that bulging congressional anthology of legislating by example.

The Senate Environment and Public Works Committee last week unanimously adopted a bill to overhaul -- "reform," if you will -- the costly federal policy of leasing office space.

But, first, like the prospective dieter who must make one last pass at the bonbons, the committee also approved a building project for Milwaukee that the reform bill would have made unacceptable.

Egged on by Rep. Henry S. Reuss (D-Wis.), who in other contests has himself been known to assail federal spending, the Senate committee agreed to lease office space in Milwaukee for $123 million over 20 years.

The Milwaukee scheme, with its false economies, its politics and its potential for abuse, is the kind the Public Building Act of 1980 is designed to stop.

If the federal government built a Milwaukee structure, it would spend $64 million, as opposed to the $123 million the new leasing project would cost over 20 years. If it continued to house its employes in presently leased space, it would spend $24 million in the 20-year period.

Federal workers in Milwaukee are located in a number of separate buildings, all considered by the Senate committee staff as "good" to "high quality" for annual rent of $1.2 million.

But the General Administration, responding to city pressure for help in a downtown renewal plan, decided to put the white-collar force in a single building, which a private developer would construct and lease to Uncle Sam.

This lease-construct method dates back to the Johnson administration, when budget officials decided to "save" money by leasing, instead of building, new federal office quarters.

As a result, major federal construction has almost stopped and the government's annual rent bill has climbed to $600 million and will reach $1 billion in 1983.

The new legislation, brainchild of Sens. Robert T. Stafford (R-Vt.) and Daniel Patrick Moynihan (D-N.Y.), would move the government back into the space construction business and push individual projects farther from the political arena.

Their bill, approved 14 to 0 last week, would establish a financing program through which the GSA would borrow money from the Treasury and require full congressional approval of every proposed new structure.

As it is now, GSA does all its negotiating in secret and needs only approval of the House and Senate Public Works committees to proceed. The government is left with rented space and a stack of rent receipts.

"The present lease-construct method, now heavily used . . . is a deep concern whether one looks first in government for efficiency and savings or for honesty and open dealing," Stafford said last week.

Consider the Milwaukee project that officials, including Reuss, say is a "linchpin" for the redevelopment program. Without the building, they say, the renewal plan might collapse.

Under the present system, GSA draws up a prospectus for a building deal and takes it to the House and Senate committees for review and approval. But the committees concede their review is perfunctory -- GSA refuses to give them details of the cost negotiations.

That secrecy would be prohibited by the Stafford-Moynihan bill. That, however, is just one side of the Milwaukee classic.

In June 1976, the committees approved a GSA prespectus for Milwaukee that called for a 20-year lease costing the government $75.7 million -- or $11.58 per square foot.

By last December, with the building still not underway, the cost had escalated to $18 per square foot.

It was the same building, in the same spot, with the same terms. But the projected cost had increased 55 percent in 18 months -- an inflation rate still not thoroughly explained by GSA to the committees. Under the present rules a new prospectus and fresh congressional approval are required. These things generally take time.

But this time they didn't; a new prospectus appeared in a political flash, which is another side of the federal building program the Senate's bill would deter or stop.

Reuss is Milwaukee's congressmen. On Dec. 14. as chairman of the House Banking Committee, he was overseeing the Chrysler Corp. financial bailout bill badly wanted by the Carter administration.

That same day, GSA drew up its amended prospectus, and Carter's Office of Management and Budget approved the prospectus, with speed that led Sen. Alan K. Simpson (R-wyo.) to speculate that an all-time record had just been set.

By that afternoon, the OMB-approved prospectus reached Capitol Hill. Reuss began a personal lobbying exercise to win House and Senate committee approval of the new deal.

Reuss didn't like what he was doing, but his city's renewel plan was in a bind. He told the Senate committee on Dec. 17, "This is a world I never made. It was the only game in town in 1978, the least construction method . . . I hope that Milwaukee won't be thought of as the last of the old order."

Christmas recess prevented the committees from approving the Milwaukee prospectus in December. But Reuss kept plugging and, with House approval in hand, he showed up to plead once more at the Senate last week.

The vote was 6 to 3 for Milwaukee. Moynihan was for it, Stafford and Simpson were against it.

The Stafford-Moynihan bill would phase out the lease-construction arrangements, like Milwaukee's, now used so widely by GSA. The agency strongly opposes this part of the legislation.

But leased space during the past 14 years has more than doubled and federal white-collar employment has increased only 110,000. Today, nearly half of the 2.7 million federal workers are housed in leased space.

The bill encourages GSA to renovate and acquire sound existing buildings and historic structures that would make attractive government offices. Design competitions would be used for new buildings.

"Our chief purpose is to prevent waste and restore order," Stafford said. "It should also produce buildings we can be proud of . . . More important, it can help build an agency and a program that we and the country can again be proud of."

Easier said than done. Full Senate approval of the bill is expected soon.

But House Public Works leaders are reported to be cool toward the bill. Architects are complaining about it and GSA has dug in its heels in opposition.