Ronald Reagan was famous as a movie star before being elected Governor of California in 1966 then President of the United States in 1980.
kennedy
No approval is needed. He is sworn in by any court official and becomes the president.
I have read somewhere that Obama's dream before becoming President was to be a bank manager.
Truman
George W. Bush, Jr. was Governor of Texas before becoming President of the United States.
Jimmy Carter was in the peanut business, before becoming President.
Anwar El Sadat was the president of Egypt before Hosni Mubarak. However, between Anwar El-Sadat's assassination and Hosni Mubarak becoming president, Sufi Abu Taleb was acting president for 8 days.
President Lyndon B. Johnson served the longest in the United States Senate before becoming president. He was in the senate for twelve years.
before
Lincoln's job before becoming president was as a lawyer. But he held many jobs prior to studying and becoming a lawyer. Two of them are as a clerk and surveyor.
George Washington
dwight eisenhouer