Before President Trump picked Dan Coats to be the director of national intelligence, Mr. Coats spent 24 years in Washington as a member of the House and the Senate from Indiana, serving long stints on both the Senate Intelligence Committee and the Senate Armed Services Committee. He had also been ambassador to Germany.

His predecessors included James Clapper, an Air Force lieutenant general who previously headed two other intelligence agencies , and Adm. Dennis Blair, who commanded United States naval forces in the Pacific.

After an increasingly difficult tenure, Mr. Coats is stepping down and Mr. Trump has chosen as his replacement Representative John Ratcliffe of Texas.

The 2004 law creating the position of director of national intelligence says that whoever holds the post must have “extensive national security expertise,” but Mr. Ratcliffe has been a House member only since 2015 and joined the House Intelligence Committee just this year. Before that he was a small-town mayor and a United States attorney, apparently with little or no experience dealing with terrorism or national security issues. He may have even falsely claimed to have prosecuted terrorists.