Washington — President Bush signed into law this morning legislation that aims to avert a shortfall in student loans.

The law, which the House and Senate passed swiftly and which Mr. Bush endorsed in a radio address, seeks to stem the departure of loan companies from the federally guaranteed student-loan program and to reassure families that student loans will be available in the fall. More than 50 lenders have left the federal program in recent weeks, amid a credit crunch that has spread from the housing market to the student-loan industry.

To encourage lenders to remain in the federal program, the law allows the secretary of education to buy loans that lenders have struggled to sell to investors. The law also clarifies that the Education Department has the authority to advance federal funds to guarantee agencies, so those agencies could make loans, if necessary, under a “lender of last resort” system.

The law will ease the process of applying for a student loan under such a system, allowing the secretary to designate emergency lenders of last resort on a collegewide basis, rather than student by student. —Kelly Field