When Lawrence A. Hough was rowing his way to two world championships and an Olympic silver medal in the 1960s, he made it look as if the current was with him.

Now, as he takes over as president and chief executive of the Student Loan Marketing Association, he faces some tricky water that may challenge his skills as a navigator.

Not that the company is in trouble financially, or that there is any shortage of demand for its services. Sallie Mae, as it is widely known, is the nation's largest buyer of government-guaranteed student loans, and as such is the largest single provider of funds for education loans.

Sallie Mae has grown from a $12 billion to a $39 billion corporation over the past six years, and its stock price has quintupled. Last week the stock was among the 10 most heavily traded on the New York Stock Exchange, closing Friday at $46.50, down $7.50.

But Sallie Mae is what is called a "government-sponsored enterprise," whose debts and other obligations are implicitly guaranteed by the federal government. Like most GSEs, Sallie Mae is congressionally chartered but is owned by private stockholders. This government relationship allows it to borrow money at favorable rates, since the market assumes that the government would make good on any default.

In the wake of the savings and loan crisis, where an explicit guarantee is costing the taxpayers hundreds of billions of dollars, the Bush administration and some in Congress want to reduce what they see as the potential risk to federal budget posed by the GSEs.

The administration plan would force the GSEs to obtain triple-A credit ratings based on their own books and without reference to their government relationship. It would place regulation in the hands of the Treasury Department, and it would require that the value of their government relationship be quantified and placed on the federal budget.

Many of the GSEs, especially the Federal National Mortgage Association and the Federal Home Loan Mortgage Association, have vigorously attacked the plan.

Hough has been more circumspect, saying in an interview only that the plan is "unlikely to be implemented exactly" as proposed and is therefore hard to comment on. However, he noted in testimony before the Senate Banking Committee Friday that Sallie Mae already has a triple-A rating, "one of a very small number of financial institutions that has."

However, in an unfortunate piece of timing last week, a large student loan guarantee organization to which Sallie Mae had extended an $865 million line of credit applied to the Education Department for assistance. That spooked Sallie Mae's investors, resulting in the sharp decline in the company's stock and adding to the cries of worry about risky GSEs.

Sallie Mae has insisted that its loans are fully collateralized and there is little risk to it. Indeed, Hough may be able to turn the problem to his advantage. Sallie Mae has proposed to take over the troubled guarantor, giving Sallie still another important role in the student loan marketplace.

The company has indicated in the past that it would like to become a vertically integrated student loan marketplace. It sought to acquire a savings and loan through which it could become a direct lender, and though that was blocked by congressional opposition, the government may have little choice but to allow it to become a guarantor.

Hough, for his part, stresses the importance of Sallie Mae to the continuing well-being of the guaranteed student loan program.

"The underlying student loan program continues to be one of enormous complexity. And as such there are needs in the marketplace, representing both the students and the educational institutions, in insuring that financial aid is there when they need it," he said.

Hough, 46, has been with Sallie Mae since 1973, and had been executive vice president for marketing, servicing and systems since 1984. He holds a bachelor's degree in engineering from Stanford University and a master's from the Sloan School of Management at Massachusetts Institute of Technology.

Joining him at the top of Sallie Mae's management is Albert L. Lord, who was named chief operating officer. Lord joined the company in 1981 and had been chief financial officer before assuming his new position.