Elon Musk and his Department of Government Efficiency have been granted access to a sensitive Treasury Department payment system containing personal data of millions of Americans receiving tax refunds,

The world's richest person is leading Trump's federal cost-cutting efforts under the so-called "Department of Government Efficiency" (DOGE).

In a letter to the Treasury secretary, the Democratic senator warned against meddling with a system that processes trillions of dollars of transactions.