Government “safety net” programs like Social Security and food stamps have pulled growing numbers of Americans out of poverty since the mid-1990s. But even before the current recession, these programs were providing less help to the most desperately poor, mainly nonworking families with children, according to a new study by the Center on Budget and Policy Priorities, a private group in Washington.

The recession is expected to raise poverty rates, economists agree, although the impact is being softened by the federal stimulus package adopted this year, which temporarily expanded measures like food stamps, child tax credits, unemployment benefits and housing and tuition aid.

In view of the gloomy employment report last week, economists are debating whether to increase stimulus funds over all. But in a side argument, poverty experts are also asking whether elements of the package aimed at the most vulnerable Americans should be extended beyond their scheduled expiration in two years or even made permanent.

The new safety-net study found that federal aid programs had helped tens of millions of Americans stay afloat in recent years, especially those with low-end jobs who benefited from rising tax credits.