(Bloomberg) -- Hunger is rising this holiday season with the U.S. Census Bureau estimating more than 21 million Americans didn't have enough to eat in early December as pandemic relief payments run out and grocery prices rise.

Low-income families may soon face more pressure with monthly child tax credit payments ending and the Senate deadlocked on legislation to extend the program backed by President Joe Biden.

The number of households in which there was sometimes or often not enough to eat reached 9.7% this month, a five month high, according to data collected between December 1 and 13 by the U.S. Census Bureau’s Household Pulse Survey. That figure in households with children sunk from 11% to 7.8% in August, after the first child tax credit monthly payments went out.

Read more: What families are actually using the child tax credit payments for

Grocery prices in the U.S. are up 6.4% from a year earlier. Food banks are also seeing a rise in demand, and clinics meant to help malnourished and underfed children have seen an increase in patients.

The child tax credit payments serve as an advance on the tax return received by two-parent households making less than $150,000 per year. Parents receive $300 monthly for each child under the age of 6, and $250 per month for each child under 18. Households making more than that get a smaller credit. The majority of parents have reported using the mid-month cash infusions for food, according to Census Bureau surveys between July and September. Studies have found making the payments permanent could significantly reduce childhood poverty. 

The last of the scheduled payments for the expanded child tax credit were sent out on Dec. 15. The Build Back Better Act includes language that would extend payments through 2022. The bill’s status is up in the air, however, after Senator Joe Manchin, a Democrat from West Virginia, on Sunday said that he would not vote for it.

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