WASHINGTON  Four months ago, it appeared all but certain that the White House and Democrats in Congress would succeed in overhauling the student loan business and ending government subsidies to private lenders.

President Obama called the idea a “no-brainer” last fall, predicting it would take billions of dollars from the profits of private lenders and give it directly to students, and many colleges were already moving to get loans directly from the federal government in anticipation of the next move by Congress.

But an aggressive lobbying campaign by the nation’s biggest student lenders has now put one of the White House’s signature plans in peril, with lenders using sit-downs with lawmakers, town-hall-style meetings and petition drives to plead their case and stay in business.

House and Senate aides say that the administration’s plan faces a far tougher fight than it did last fall, when the House passed its version. The fierce attacks from the lending industry, the Massachusetts election that cost the Democrats their filibuster-proof majority in the Senate and the fight over a health care bill have all damaged the chances for the student loan measure, said the aides, who spoke on the condition of anonymity because they were not authorized to discuss the matter publicly.