The Trump administration has demoted its top Internal Revenue Service lawyer and replaced him after the Department of Government Efficiency received pushback while trying to obtain confidential taxpayer information.

William Paul, a civil servant who became the acting chief counsel at the I.R.S. in January, is expected to be replaced by Andrew De Mello, the people said. In his first term, President Trump nominated Mr. De Mello to serve as the inspector general of the Education Department.