THE SENATE child care bill was supposed to benefit mainly neglected lower-income working families with children. Sponsors pointed out that children had been allowed to fall behind in recent years, while Congress did well by other needy groups, the elderly especially. The children's poverty rate is about 20 percent, highest for any age group. This bill would help restore the balance.

But guess what happened to the legislation on its way to conference, where it is now stuck. The supposed children's bill sprouted a new provision. Almost half the benefits it would confer would go, not to the young, but to the elderly and mostly to the relatively well-off elderly at that.

The bill includes a liberalization of the Social Security earnings test. The earnings test requires that a person be genuinely retired to qualify for benefits; a person who continues to earn more than a certain amount will have his benefits reduced. Liberalization has long been a goal of conservatives particularly. They argue that the elderly are a valuable resource who ought to be encouraged to contribute economically as long as possible and that it's wrong to penalize a willing worker, particularly one who needs the extra money. In fact the law does not penalize people of marginal means who need the extra money; they are still allowed to earn. The Congressional Budget Office has repeated that most of the considerable cost of liberalization would be conferred on elderly households in the highest and next-to-highest income quintiles. The proposition nonetheless is hard to vote against, and sponsors agreed to include it in the bill in part for lack of votes to fend it off.

In fairness, the Senate also financed it. The bill would raise the necessary money by requiring that state and local government employees not participating in a retirement plan be enrolled in Social Security and begin to pay the associated taxes. Technically, the proposal for the elderly thus doesn't come at child care's expense. It's still the wrong way to spend the next federal dollar.

If the conferees can find some extra money, they should use it to support the child care provisions of the bill. This is already under strain. House and Senate together have proposed more benefits than there is money for. The most important is a House proposal to expand the earned-income tax credit for the working poor with children. This is a) in danger of being cut back to make room for a scattering of lesser provisions, and b) in danger of being used by the budget negotiators for the White House and Congress to compensate the poor for an excise tax increase. They would be left with no net gain.

The Democratic leadership and White House have both said they want a child care bill, and though they differ as to size and shape, a useful array of benefits can be worked out. But the leadership will have to pay attention. The child care bill ought not be picked apart for other purposes.