In a letter to Treasury Secretary Scott Bessent on Monday, Sen. Elizabeth Warren (D-Mass.) asked why he had granted DOGE access to the system and raised a number of concerns, including the risk that the U.S. wouldn’t service its debt on time.

“This astonishing mismanagement—turning over the federal government’s entire payment system and sidelining the most senior career official responsible for managing it—also puts the country at greater risk of defaulting on our debt, which could trigger a global financial crisis,” she wrote.

The system has been likened to the government’s checkbook and makes $6 trillion in disbursements a year. That includes everything from Social Security checks to government salaries to interest payments on Treasury bonds.

On Sunday, Musk said DOGE is shutting down payments to federal contractors, including money for a religious charity that provides social services to refugees.

Career civil servants have typically overseen the payment system, and DOGE’s attempt to gain access to it was met with resistance by the Treasury Department’s highest-ranking career official, David Lebryk, who was placed on administrative leave before he abruptly announced his retirement on Friday, sources told the Washington Post.

His departure comes as the federal government has hit its $36 trillion debt ceiling, forcing the Treasury Department to begin using “extraordinary measures” last month to avoid a debt default by temporarily halting other payments into certain accounts.

Warren, who is the ranking member on the Senate Banking Committee, highlighted Lebryk’s role in managing the Treasury’s cash flows, including those extraordinary measures that prevent default.

“The fiscal assistant secretary—unlike the amateurs you have empowered in forcing him out—was well prepared to manage these kinds of crises,” she added.

Musk’s DOGE surrogates have access to the payment system but don’t have operational control yet, sources told the New York Times. That’s after they were made Treasury employees, passed background checks, and got security clearances.

The Treasury Department and the U.S. DOGE Service, which was reorganized from the U.S. Digital Service to enact DOGE’s agenda, didn’t immediately respond to requests for comment.

President Donald Trump said Monday that Musk can highlight potential spending problems but can’t stop payments on his own.

“Elon can’t do and won’t do anything without our approval,” he told reporters. “If there was something that didn’t have my okay, I’d let you know about it really fast.”

Warren also flagged other concerns that handing over the system’s access to DOGE could create, including the flow of Social Security checks, tax refunds, and Medicare benefits as well as political favoritism and private financial information that’s protected by law.

Her letter comes after Sen. Ron Wyden (D-Ore.) sent a letter on Friday to Bessent raising similar worries.

“To put it bluntly, these payment systems simply cannot fail, and any politically motivated meddling in them risks severe damage to our country and the economy,” he wrote.