The nation's food stamp program is an essential part of the American safety net. Why? Because people can't be productive — in school, at work or looking for work — if they are hungry and fearful about not having enough food to feed their families.

The program serves 46 million people, almost as many people as Medicare. And that's despite the fact that more than one-third of those eligible for the benefit are not receiving it. If all those who qualified for food stamps enrolled in the program, it would include 20 percent to 25 percent of Americans.

Not surprisingly, given the large numbers who participate, food stamp recipients are a diverse bunch, including the elderly, the disabled, one-parent families, two-parent families, low-wage workers, students, soldiers and the unemployed.

But if Republicans have their way, they will turn food stamp recipients into the new "welfare queens."

The conservative Heritage Foundation has reprised the false charges once leveled at welfare, suggesting that food stamps may make recipients "dependent on government." And Republican presidential candidate Newt Gingrich has said that "the African American community should demand paychecks and not be satisfied with food stamps." (This, despite the fact that only 22 percent of food stamp recipients are black.)

Republicans have proposed limiting lifetime use of food stamps, rolling back spending on the program and requiring food stamp recipients to hold jobs. Former Pennsylvania Sen. Rick Santorum promised on the campaign trail to roll back the food stamp program "just like I did with welfare" in the 1990s. Facing these attacks, the Supplemental Nutrition Assistance Program (as food stamps are officially known) stands at a crossroads. Will the program go the way of welfare, or will it follow a different path? If it is to survive, its supporters would do well to study history.

Food stamps were first conceived during the Depression as part of a Keynesian approach to priming the economic pump. And it was the grocery industry, not social welfare advocates, that pushed for them. The architects of the program emphasized that it bolstered household consumption and shored up the retail economy.

Food stamps aimed to replace the government's in-kind food distribution, which had forced the hungry to line up for government cheese and excess produce, sometimes off the back of trucks. Grocers preferred to have people standing in lines in their stores than standing in lines to take surplus food. Once the program was started, the grocery industry advertised the stamps to homemakers as smart, money-saving shopping tools.

Today's food stamp users are issued debit cards they swipe at the register just as other consumers do. And retailers across the spectrum, from swanky Whole Foods to cost-conscious Sam's Club, accept them because it's good business. The program allows grocery sellers to keep customers who otherwise might not be able to afford today's rising food prices.

Food stamp redemptions are good for retailers. In 2009, they pumped $50 billion into the economy. And, according to a 2008U.S. Department of Agriculturepublication, the benefits extend beyond stores: "Every $5 in new food stamp benefits generates a total of $9.20 in community spending," and each "$1 billion of retail food demand by food stamp recipients generates 3,300 farm jobs."

History suggests that the pernicious anti-welfare rhetoric that has recently been attached to the program will prove powerful and could threaten to discredit it.

With the increasing protest against economic inequality across the country, the "99 percent" should defend food stamps as a crucial pillar of the American promise and as something good for the economy. In today's hard times, with growing poverty and rising food prices, there is widespread recognition that making ends meet is no small feat, even for the middle class, and that food stamps are essential.

Conservatives are trying to smear Barack Obama by dubbing him the "food stamp president." He should not run from the label but embrace it, positioning himself as a defender of American retailers and a protector of the security and integrity of all U.S. households.

Lisa Levenstein is an associate professor of history at the University of North Carolina at Greensboro and the author of "A Movement Without Marches: African American Women and the Politics of Poverty in Postwar Philadelphia." Jennifer Mittelstadt is an associate professor of history at Rutgers University and the author of "From Welfare to Workfare: The Unintended Consequences of Liberal Reform, 1945-1965." This article originally appeared in the Los Angeles Times.