The confirmation of a Musk associate's access to the system codes came in a letter from a Treasury official to Democratic Senator Ron Wyden that said the review was being undertaken to "maximize payment integrity for agencies and the public".

Treasury Secretary Scott Bessent has not commented on reports in recent days that Musk's informal Department of Government Efficiency had gained access to the system responsible for disbursing more than $6 trillion of annual government spending.

Several thousand people gathered outside the Treasury on Tuesday to protest DOGE's Treasury access amid his sweeping incursion into government operations, which this week led to the shutdown of the U.S. Agency for International Development, merging its aid mission into the State Department.

The payment system review "is not resulting in the suspension or rejection of any payment instructions submitted to Treasury by other federal agencies across the government." Jonathan Blum, principal deputy assistant secretary in the Office of Legislative Affairs wrote to Senator Ron Wyden, of Oregon.

"In particular, the review at the Fiscal Service has not caused payments for obligations such as Social Security and Medicare to be delayed or re-routed," Blum's letter said.

The DOGE team at Treasury conducting the review is led by technology firm chief executive Tom Krause, whom the letter described as a "Treasury employee." Krause is CEO of Cloud Software Group, which owns former independent software firms Citrix and Tibco.

Wyden raised alarms over the weekend when reports first surfaced that a team under the direction of Musk, appointed by President Donald Trump to conduct a broad review of government operations.

"I’m sure the Treasury Secretary and the president want to save face and downplay the risks as Elon Musk seizes power, but nothing they’re saying is believable or trustworthy," Wyden said in response to Blum's letter.

ANGER VENTED

Outside the Treasury, protesters waved placards with slogans including: "Nobody Elected Musk" and "Bessent, you have 1 job!! Protect our money. You already failed."

About three dozen Democratic members of the Senate and House of Representatives tried to enter the Treasury to confront Bessent on the issue but they said they were denied access.

"Elon Musk is seizing power from the American people. We are here to fight back," said U.S. Senator Elizabeth Warren.

Rebecca Weiss, who lives in suburban Maryland, told Reuters that she attended the protest because she is worried about what Musk will do with the payments data.

"He's obviously a data guy, and now he has access, potentially, to everybody's personal identifiable information, which he might take advantage of for his business purposes," she said. "The bottom line is, we didn't elect him. He's muscled in illegally in a place that he's not authorized."

Democrats earlier on Tuesday vowed to push legislation to deny "special government employees" such as Musk access to sensitive government records.