After struggling with soaring heating costs through the winter, millions of Americans are behind on electric and gas bills, and a record number of families could face energy shut-offs over the next two months, according to state energy officials and utilities around the country.

The escalating costs of heating oil, propane and kerosene, most commonly used in the Northeast, have posed the greatest burdens, officials say, but natural gas and electricity prices have also climbed at a time when low-end incomes are stagnant and prices have also jumped for food and gasoline.

In New Hampshire, applicants for fuel subsidies under the federal Low Income Home Energy Assistance Program received an average of $600 in a one-time grant and up to $975 for the extremely poor who rely on heating oil or propane, the costliest fuels. But those grants, which in recent years have covered 60 percent of heating costs, covered only about 35 percent of those costs this winter, said Celeste Lovett, director of the state’s energy aid program. The state will have given aid to about 34,500 people by the end of April, Ms. Lovett said, a 5 percent increase over last year and the highest number ever.

The most immediate challenge is to help the high number of consumers who are far behind in electric and gas payments, said Mark Wolfe, director of the National Energy Assistance Directors’ Association, which represents state aid officials in Washington.