Financial aid officers are starting to worry about a program that is supposed to provide more than $30 billion next year to college students.

“Our students count on that money, and we don’t have the resources to try to make that up,” said Alice Murphey, director of financial-aid management at the City University of New York. “There’s always been a lot of support in Washington for Pell, and enough people on our side. This is the first time it’s ever looked like there wouldn’t eventually be a solution.”

Most students and parents are unaware of the uncertainty regarding the grants, Ms. Murphey said, but if they were cut, the reaction would be intense.

“I think there would be a huge rebellion,” she said.

Bigger Pell grants have been a priority of the Obama administration, part of its commitment to expanding access to college and building a better-educated work force. But with the recession sending more students back to school, the number of unemployed and low-income students eligible for Pell grants has grown rapidly  and with it, the gap in financing.

“Next year, there will be 8.7 million Pell recipients, and the cost of the program will be about $34 billion,” said Terry Hartle, senior vice president at the American Council on Education, who is lobbying for full financing for Pell grants. “It’s more than doubled in five years. Congress has two choices now: they can add $5.7 billion more and keep the maximum award, or they cannot provide it and let the Pell for next year fall.”