Musk and Trump have said they aim to reduce the $6.7 trillion federal budget by $1 trillion, but Trump has also promised not to reduce benefits for seniors who get Social Security retirement payments and participate in the Medicare health plan. Those two programs accounted for more than one third of federal dollars spent in the last fiscal year. While they are projected to eat up more of the budget as the population ages, trimming them would anger millions of Americans.
"There is no way to meet their goals without hitting the third rail," said Lauren Bauer, a researcher at the Brookings Institution who tracks the Treasury Department's daily spending statements.
Musk has said he will scrutinize both programs for fraud, but his attempts to scrutinize sensitive payment and personnel records have raised security and privacy fears. On Wednesday, 21 career workers in DOGE resigned in protest, saying the agency had mishandled Americans' private data.