Ryan's budget says the Pell grant program, currently costing about $36 billion a year, is unsustainable.
"Urgent reforms are necessary to enable the program to continue as the foundation of the nation's commitment to helping low-income students gain access to higher education," budget documents say.
Obama also proposed keeping interest rates at 3.4 percent for subsidized Stafford loans for undergraduates. After initial Republican hesitation, Romney endorsed the idea and Congress eventually approved it. Ryan's budget would have let the rates double to 6.8 percent, as was scheduled under previous law.
Associated Press writer Julie Pace contributed to this report.
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