 A presumptive nominee has never announced their departure from the race so close to the election. In 1968, President Lyndon Johnson announced that he would not seek reelection, but he did that in March. Democratic Congressman James Clyburn was on CNN's State of the Union before the announcement and said for any change to top the ticket to work, they must avoid an open convention on August 19th. It will come out the same way it came out in 1968, 1972, and 1980.