The Trump administration’s plan to move the government’s HR office to the General Services Administration would undermine the neutrality of the federal workforce, according to a group that represents about 7,000 career executives in the federal government.

The administration hasn’t made the case for making the Office of Personnel Management subordinate to the GSA, Bill Valdez, president of the Senior Executives Association, said in a letter to Reps. Gerry Connolly (D-Va.) and Mark Meadows (R-N.C.), the chairman of the House Oversight and Reform Subcommittee on Government Operations and the subcommittee’s top Republican. The SEA released the letter May 20, on...