Two top operatives with Elon Musk’s cost-cutting initiative have been transferred from the Social Security Administration to the Justice Department’s immigration enforcement unit as part of a widening White House effort to use personal data to target undocumented immigrants, according to officials briefed on the move.

The operatives, Jon Koval and Payton Rehling, have been working on an embedded team from the Department of Government Efficiency that has tried to gain access to highly sensitive Social Security data with the purported goal of reducing government waste. So far, that effort has fallen short of its cost-cutting predictions.

Mr. Koval, a 2020 business school graduate, and Mr. Rehling, a computer and machine learning specialist, will be responsible for scouring Social Security databases for information on thousands of undocumented immigrants already subject to deportation proceedings, according to a senior administration official with knowledge of their assignments.

A Justice Department spokesman declined to comment.

The department has been given a vastly expanded role in immigration enforcement under President Trump. He has ordered federal prosecutors to prioritize criminal violations related to immigration, investigate local governments that obstruct enforcement and expel migrants by revoking their Social Security cards after falsely listing thousands of them as dead in databases.

An internal memo outlining Mr. Koval’s temporary, 120-day transfer to the Justice Department was drafted on Tuesday, the same day that Mr. Trump issued an executive memo blocking migrants from obtaining Social Security benefits and directing the department to redeploy prosecutors in 50 U.S. attorneys’ offices to bring criminal cases and initiate deportations.

The memo, obtained by The New York Times, described broad, and unspecified, authority in “reducing the immigration case backlog,” and said Mr. Koval would continue to work on projects “related” to Social Security.