Iowa U.S. Senator Chuck Grassley met Monday with President Trump’s nominee for commissioner of the Internal Revenue Service, who he says has “very aggressive plans” for overhauling the agency.

Sen. Chuck Grassley, chairman of the Senate Judiciary Committee, sent UnitedHealth Group CEO Andrew Witty a letter demanding detailed information on the company’s Medicare billing practices Monday.

During a conference call Tuesday with Iowa reporters, U.S. Senator Chuck Grassley recalled having been fired several times, decades ago when he worked in the private sector. “It’s a tragedy ...