Dana Mibank: The words that could end a presidency

Video: Following the deposition of William B. Taylor Jr., the U.S. ambassador to Ukraine, Rep. Eric Swalwell (D-Calif.) spoke to reporters on the ambassador’s opening statement. (The Washington Post)

Lean and bespectacled, with neatly combed gray hair and a pressed charcoal suit, William Taylor, the acting U.S. ambassador to Ukraine, gave not so much as a glance toward the massed cameras as he arrived Tuesday, escorted by uniformed police, at the offices of the House Intelligence Committee. With steady gait and grim countenance, he disappeared behind a basement door marked "Restricted Area."

"In August and September of this year, I became increasingly concerned that our relationship with…