The acronym POTUS (the "O" being long, as in "toe") is in common parlance in the White House today, used by in-the-know staffers to refer to the President of the United States. It is never uttered in addressing him face-to-face. POTUS long ago existed in the telegraph code that was a bible of the major news wires. And it is said that when President Franklin D. Roosevelt traveled on the Pennsylvania Railroad in his private car, Magellan , POTUS was the cover word employed to identify this important passenger. "POTUS to PRIME" was sometimes the heading of FDR's aides—not the president himself—placed on his correspondence with Prime Minister Churchill in the era of World War II.
POTUS's public emergence began when buttons on White House phones linked directly to the president were labeled thus in President Lyndon B. John-son's time. The word came into currency during President Jimmy Carter's term, and it was picked up as shorthand by the Secret Service, matching SCOTUS which was becoming the favorite acronym for the Supreme Court of the United States. Nancy Reagan inspired but may not have originated FLOTUS (rhyming with POTUS) to specify the First Lady. VPOTUS (pronounced vee-potus) to indicate the vice president was occasionally heard in the same era to refer to George Bush, then holding office. Its use became ordinary when Al Gore was vice president in Bill Clinton's administration. The word VEEP to describe the vice president became popular in President Harry Truman's day as a nickname for Vice President Alben W. Barkley, being simply a contracted pronunciation of VP, the common abbreviation for vice president.