From the start of his second term, President Trump has bet that he can appeal to low-income voters while slashing safety net programs on which many of those voters depend.

The enormous tax-and-spending bill he is trying to push through Congress is a high-stakes test of that proposition, a gamble that Mr. Trump can retain the loyalty of his blue-collar supporters despite moves that could harm their immediate economic self-interest.

As approved by the House, the legislation cuts hundreds of billions of dollars in food benefits and removes nearly 11 million people from the health care rolls, while offering large tax cuts skewed to the rich and adding trillions to the national debt. Senate Republicans are considering a similar measure, with bigger Medicaid cuts and smaller reductions in nutritional aid.

Whether Republicans succeed in passing the bill — and whether voters punish them for lost assistance — could affect next year’s congressional elections and determine the long-term size and strength of the social welfare system.

Once mostly aimed at the indigent, aid programs were often derided by conservative critics as Democratic handouts for minority groups in urban areas. But some benefits now reach up the income ladder to working-class households, which Republicans increasingly court.

Enrollment has roughly doubled in two decades in Medicaid and food stamps (formally, the Supplemental Nutrition Assistance Program, or SNAP). The Affordable Care Act, signed in 2010 by President Barack Obama, subsidized households up to 400 percent of the poverty line, and pandemic-era subsidies, which expire this year, went higher.