Students are being hit on another front: Many banks that are still making private loans are tightening their standards. Among other factors, lenders consider a loan applicant's so-called FICO score, a measure of creditworthiness used to rate consumers on a 300-to-850 point scale. Some student borrowers say that, in recent years, they have qualified for private loans with FICO scores in the 600-point range.

This year, some lenders have raised that threshold by as much as 100 points, according to financial-aid administrators and industry analysts. The hike is especially troubling for younger college students who haven't had a chance to build up a good credit score.

This could leave as many as 200,000 students ineligible for private loans this fall, says Mark Kantrowitz, publisher of Finaid.org, a Web site devoted to financial aid. Kantrowitz came to this estimate by using publicly available information to track securities backed by student loans. He then counted the number of those borrowers with credit scores that don't meet the tougher standards.

With only a few weeks before classes begin, "students are definitely having more trouble finding the lenders," says Kantrowitz, who has testified before Congress on aid issues.

Easier access to student loans has helped advance the American dream of college education for all. More than two-thirds of high-school graduates went right to college in 2006, up from fewer than half in 1980, according to the Department of Education's latest tally. Another recent federal report indicated that 44 percent of all adults were taking classes of some kind, up from 33 percent in 1991. But that trend, like the notion that everyone should own their own home, is under pressure now.

Credit rater Standard & Poor's last month warned that problems with private student loans could be widespread this year, causing some students to drop out of college. Its report added that if the economic downturn leads more students and families to default on their loans, the availability of such funds may dwindle further.