Treasury Secretary Scott Bessent gave Mr. Musk’s representatives at the so-called Department of Government Efficiency a powerful tool to monitor and potentially limit government spending.

Mr. Trump has said he plans to nominate Billy Long, a former Republican congressman, to the role.

The president-elect told Republicans from New York, New Jersey and California to come up with a plan for increasing the state and local tax deduction — a move that would benefit their constituents.

President-elect Donald J. Trump has moved beyond the team-of-rivals approach from his first term and chosen economic aides who will defend tariffs and tax cuts.

President-elect Donald J. Trump has waffled on his preferences for how his party tackles his agenda, adding to the uncertainty for Republicans.