The broad outlines of the Carter administration's housing and urban policies are beginning to emerge on Capitol Hill.

In private budget discussions with key congressional leaders, administration emissaries have promised to seek a huge, one-shot stimulus immediately that would subsidize between 130,000-200,000 additional low-rent apartment units this year. On top of this, they plan to ask for 400,000 subsidized units for the coming year, including 50,000 new units of traditional public housing - a program once "killed" by President Richard M. Nixon.

They also have proposed a big, $500 million increase in money for distribution to cities and other jurisdictions under the community development block grant program, including creation of a potentially controversial $400 million special discretionary fund for use by the Department of Housing and Urban Development, and an alternative fund allocation formula. The special fund and most other block grant changes would be designed to aid the large, northern cities - such as the District, Newark and Boston - that might otherwise suffer under the program's existing fund arrangements

The budget discussions thus far on Capitol Hill have been dominated by what appear to be the White House's and HUD Secretary Patricia Roberts Harris' - principal themes for the housing and urban areas for the foreseeable future:

The need for the Federal government to support a high, steady volume of production (400,000 to 600,000 units annually) of dwellings for low-income Americans as a matter of policy, not as a counter-cyclical economic tool;

The need for "continuity" of all the basic programs, in urban development as housing, rather than "totally reshuffling the deck every two or three years," as one HUD official put it;

The need for greater visibility for housing and urban issues, in the White House and cabinet, as well as on Capitol Hill.

Each of these themes differs from those predominant in the Ford and Nixon administrations. Harris and her advisers see subsidized housing essentially as a social welfare function, rather than as on eof the levers available to the Treasury and the Council of Economic Advisers to push or not to push as the country's economic temperature rises or falls. Only by producing a dependable, year-in and year-out supply of low-rent and moderate-cost housing can that basic social welfare purpose be achieved.

When programs are turned off and on for fiscal reasons - as in the early 1970's when a federal "bust" followed close on the heels of an unprecedented boom in housing subsidy spending - nobody's purpose is served, they believe.

The new administration's second major theme - continuity of established programs - means that many of the Republican-designed (or administered) housing and urban assistance approaches will be with us for a few more years, at least. This includes the "Section 8" leasing assistance program, a product of the late Nixon years that now is the country's largest single housing aid vehicle; the revised Section; 235 mortgage interest subsidy program( and the "tandem" middle income mortgage aid approach.

The third theme - higher visibility for housing and urban programs -could prove to be the most difficult to carry out. HUD Secretary Harris plans, according to one aide, to be less involved in the dotting of "i's" and personal rewriting of departmental regulations than her immediate precessor, Carla A. Hills. She plans instead to delegate much of this to her designated under secreatry, Jay Janis, while spending proportionately more time working inside the Cabinet - meeting with the leaders at Treasury, Federal Reserve Board, the Council of Economic Advisers, the White House domestic affairs staff and others who indirectly - but decisively - affect the economic health of cities and the housing industry.

Harris inevitably will be asking for more federal dollars for the cities and for housing as part of her consciousness-raising effort. More money, as Management and Budget director Bert Lance has pointed out since arriving on the scene last month, cannot be every department head's constant refrain, because money just isn't readily available.

(Lance offered insight into what may be Jimmy Carter's predisposition in the economic area when he recently reminded reporters that "Jimmy Carter runs liberal, but governs conservative.")

Whether Harris can ensure that OMB and the White House treat housing and the cities "liberal," rather than "conservative," should be a fascinating process to watch.

Kenneth R. Harney is managing editor of the Housing and Development Reporter, published here by BNA, Inc.