The Office of the First Lady of the United States is largely a ceremonial position that has traditionally been filled by the wives of sitting Presidents. Marriage to the President is not required to be appointed as the First Lady, but it certainly does help. There have been moments in history when the wife of the President was unable to perform her White House duties, which required the President to appoint another woman to the post.
Originally referred to as “The First Lady of the Land”, the main job of the First Lady is to serve as White House Hostess on behalf of the President when entertaining of guests becomes necessary. In order to accomplish her chief duties as White House Hostess, the First Lady is provided with a staff consisting of a press secretary, a social secretary, the White House Chief Floral Designer, and a Chief of Staff. In her capacity as the White House Hostess, the First Lady is in charge of all ceremonial / social events at the White House .
Even though she receives no official compensation or salary for her efforts as the First Lady of the United States, several First Ladies in the past have spearheaded campaigns for traditionally neutral causes, like drug awareness education, military family issues, literacy, women’s rights, and more. First Ladies are often respected as being one of the President’s closest unofficial advisers.
In the event that the First Lady becomes unable to fulfill her duties, or if the President is a bachelor or widower, then an Acting First Lady may be appointed by the President in order to fulfill First Lady duties. Martha Jefferson Randolph, daughter of President Thomas Jefferson, served as First Lady from 1801 to 1809 because her father was a widower. Emily Tennessee Donelson, niece by marriage of President Andrew Jackson served as First Lady when her aunt, the President’s wife, died in 1828. More recently, Chelsea Clinton, daughter of President Clinton, served as Acting First Lady in the period of time between her mother being sworn into the Senate and her father leaving office. Her term as First Lady lasted for about two weeks.
In most cases, the President is likely to appoint someone in his inner circle as First Lady of the United States if he is unmarried or his wife becomes unable to fulfill her duties, but being related to the President is not a requirement of the office. The President is free to choose who he wants to fill the role of First Lady of the United States without needing the approval of the legislature.