The White House is increasing pressure on Congress to permit the Education Department to buy privately held student loans, dismissing other plans for giving money to lenders.

Three top Bush administration officials wrote lawmakers Wednesday urging quick Senate action on House-passed legislation to allow the Education Department to purchase existing loans from lenders in order to boost their ability to make new loans.

“Implementing this authority will take time so it is imperative to move this legislation without delay,” reads the letter from Education Secretary Margaret Spellings , Treasury Secretary Henry M. Paulson Jr. and Office of Management and Budget Director Jim Nussle .

The White House had already come out in support of most of the bill’s provisions, but Wednesday’s letter is a stronger signal that it is concerned about the credit crunch — and that it wants quick action. That call could goad reluctant senators into supporting the plan, which is currently stalled in the Senate.

Hit by the one-two punch of $20 billion in subsidy cuts last year and this year’s credit crunch — which is making it more expensive to raise money to make loans — more than 50 lenders have dropped out of the federally backed student lending program.

Lenders, concerned that they would lose money by selling loans at cost to the Education Department, have pressed for a more direct approach of injecting money into the market, including a plan by Sen. Christopher J. Dodd , D-Conn., to have the Federal Financing Bank, a government corporation under Treasury Department jurisdiction, to lend banks money for student loans.