The instrument is an obscure U.S. Department of Agriculture shopping list used to determine food stamp benefits, known as the market basket.

A review of the so-called Thrifty Food Plan, ordered by Biden two days after he took office, could trigger an automatic increase in benefits as soon as Oct. 1, a day after expiration of a temporary 15% boost in food stamp payments that Biden included in his $1.9 trillion Covid-relief package.

James Ziliak, director of the Center for Poverty Research at the University of Kentucky, said the re-evaluation "could result in an upward adjustment of 20% or more in the benefits." That would amount to roughly a $136-a-month increase in the maximum benefit for a family of four, which was $680 before the temporary pandemic-related increase.

"This is really meaningful," said Jason Furman, a Harvard Kennedy School of Government professor who was chairman of President Barack Obama's Council of Economic Advisers. "It's one of the bigger things government can do for poverty without Congress."