THE ADMINISTRATION would like to get more welfare mothers into the labor market and off the welfare rolls. But it also wants to cut the already scant resources devoted to such efforts. The two objectives are not compatible.

The major source of job-finding help for welfare mothers is the Work Incentive (WIN) program. Even before the Reagan administration sliced its budget, WIN was always short of funds. Still, several such programs, with the aid of special extra funds and good ideas, have recently succeeded in increasing self-sufficiency among welfare families.

With the help of an enthusiastic governor, a good labor market and extra federal and state money, Massachusetts has been able to place 17,000 welfare recipients in regular jobs over the last year and a half, for example. As a result most of these families have substantially higher incomes while the state estimates it has cut its welfare budget by $50 million. Some of those savings, however, were offset by costs of support services -- such as training, day care and transportation -- which less generous states are unwilling to bear.

A less expensive welfare job program has been operating in San Diego -- the most successful so far among several state-run work projects being evaluated by the Manpower Development Research Corporation. It can't match the placement rate of the Massachusetts program, but it has been able to produce a 30 percent increase in the earnings of new welfare mothers. MDRC, however, is quick to point out that the project has a strong staff experienced in running work programs and that it, like the other projects, depends heavily on WIN money and organization for its success -- resources that few states are likely to be willing and able to replace on their own.

For some reason, the program has aways been high on the administration's hit list. This year's White House-Senate budget accord called for eliminating WIN entirely. Now the administration has retreated to pressing for another big cut in WIN money while at the same time requiring states to develop stronger work programs. That's not a sensible strategy. Helping welfare parents support their families is surely the best way to cut both welfare costs and poverty in the long run. But any businessman will tell you that you can't expect a long-term return without up-front investment.