WASHINGTON — The Obama administration is preparing to unveil a legislative proposal for a far-reaching overhaul of the National Security Agency’s once-secret bulk phone records program in a way that — if approved by Congress — would end the aspect that has most alarmed privacy advocates since its existence was leaked last year, according to senior administration officials.

Under the proposal, they said, the N.S.A. would end its systematic collection of data about Americans’ calling habits. The bulk records would stay in the hands of phone companies, which would not be required to retain the data for any longer than they normally would. And the N.S.A. could obtain specific records only with permission from a judge, using a new kind of court order.

In a speech in January, President Obama said he wanted to get the N.S.A. out of the business of collecting call records in bulk while preserving the program’s abilities. He acknowledged, however, that there was no easy way to do so, and had instructed Justice Department and intelligence officials to come up with a plan by March 28 — Friday — when the current court order authorizing the program expires.

As part of the proposal, the administration has decided to ask the Foreign Intelligence Surveillance Court to renew the program as it exists for at least one more 90-day cycle, senior administration officials said. But under the plan the administration has developed and now advocates, the officials said, it would later undergo major changes.