WASHINGTON, Feb 2 (Reuters) - Billionaire Elon Musk, who

is heading U.S. President Donald Trump's efforts to shrink the

federal government, will give an update on the effort early

Monday amid reports he has been given access to a vital payments

system at the Treasury Department.

Musk, who is also CEO of Tesla and SpaceX plans to

discuss the Department of Government Efficiency (DOGE) in a

Monday social media talk on X, which he also owns. Trump has

assigned Musk to lead a federal cost-cutting panel.

His access to the Treasury system, first reported by the New

York Times, that sends out more than $6 trillion per year in

payments on behalf of federal agencies and contains the personal

information of millions of Americans who receive Social Security

payments, tax refunds and other monies from the government has

raised concerns about what he will do with the information.

Democrat Peter Welch, a member of the Senate Finance

Committee, called for explanations as to why Musk had been

handed access to the payment system and what Welch said included

taxpayers' sensitive data.

"It's a gross abuse of power by an unelected bureaucrat and

it shows money can buy power in the Trump White House," Welch

said in an emailed statement.

Musk has Trump's support. Asked if Musk was doing a good job

Sunday, Trump agreed. "He's a big cost-cutter. Sometimes we

won't agree with it and we'll not go where he wants to go. But I

think he's doing a great job. He's a smart guy. Very smart. And

he's very much into cutting the budget of our federal budget."

Musk's team have been given access to or take control of

numerous government systems.

Reuters reported on Friday, that aides to Musk charged with

running the U.S. government human resources agency have locked

career civil servants out of computer systems that contain the

personal data of millions of federal employees, according to two

agency officials.

Musk has moved swiftly to install allies at the agency known

as the Office of Personnel Management. A team including current

and former employees of Musk assumed command of OPM on Jan. 20,

the day Trump took office, the sources added.

Since taking office 11 days ago, Trump has embarked on a

massive government makeover, firing and sidelining hundreds of

civil servants in his first steps toward downsizing the

bureaucracy and installing more loyalists.