The Trump administration may alter the way it determines the national poverty threshold, putting Americans living on the margins at risk of losing access to welfare programs.

The possible move would involve changing how inflation is calculated in the "official poverty measure," the White House Office of Management and Budget said in a regulatory filing on Monday. The formula has been used for decades to determine whether people qualify for certain federal programs and benefits.

The measure, first set in the 1960s, is calculated at three times the cost of a minimum food diet and adjusted every year as prices rise. In 2018, a family of four making no more than $25,900 was considered impoverished. The figure determines eligibility for a wide swath of federal, state, and non-profit programs, including Medicaid and food stamps.