With the federal government mired in a shutdown, the US Department of Agriculture announced that funding for food stamps and subsidized school lunches for poor children will run out by the end of February or early March, if Congress doesn't reach a deal to reopen the government.

US Agriculture Secretary Sonny Perdue on Friday released an outline of how the government shutdown will affect the USDA's core nutrition programs, noting that the agency will try to keep them running as long as possible.

That includes the Supplemental Nutrition Assistance Program (SNAP) — also known as food stamps — child nutrition programs at school, and the Special Supplemental Nutrition Program for Women, Infants, and Children.

These programs all help poor families and students buy groceries and school lunches. For now, people who rely on these programs can still use them.

"All have funding available to operate through the month of February, and many have funds to continue operations through March, without additional appropriation," Perdue wrote in a statement.

It's unclear what would happen after the federal money runs out in the event of a prolonged government shutdown. Perdue suggested that state agencies, which oversee the programs, could continue to provide the services with their own money, or with any extra federal money they may have saved up.

Food stamps and other federal nutritional programs are considered mandatory programs but still require Congress to renew the funding every year. Other major mandatory programs — like Social Security and Medicare — are not affected by the shutdown. They are automatically funded each year.