This uncertainty was corrected after the assassination of John F. Kennedy. Under the 25th Amendment to the United States Constitution, if the President dies, the Vice President automatically becomes the President. If the Vice President dies, resigns, or becomes President, the President can appoint a new Vice President. The appointment needs to be confirmed by a majority vote of both the House of Representatives and the U.S. Senate. This has happened twice. Gerald Ford became Vice President after the resignation of Spiro Agnew, and Nelson Rockefeller became Vice President when Gerald Ford became President after Richard Nixon resigned.