In 1973 Spiro Agnew was Vice President and Richard Nixon was President. Agnew resigned due to the fact the US Attorney’s office in Baltimore MD advised his lawyers, in a letter, that Agnew was being investigated for conspiracy, extortion and bribery. It was alleged that as Governor of Maryland he accepted kickbacks on state contracts. Eventually a deal was brokered between the US Attorney’s office and Agnew and part of the deal was he would resign as VP. Once he resigned [October 10, 1973] President Nixon nominated House Minority Leader Gerald R. Ford as VP, in accordance with Section 2 of the 25th Amendment to the U.S. Constitution. Ford’s nomination was confirmed by Congress and he became the Vice President.
Section 2. Whenever there is a vacancy in the office of the Vice President, the President shall nominate a Vice President who shall take office upon confirmation by a majority vote of both Houses of Congress.
When Watergate broke, Richard Nixon resigned as President of the United States on August 9, 1974, and VP Ford became President Ford, in accordance with Section 1 of the 25th Amendment to the Constitution.
Section 1. In case of the removal of the President from office or of his death or resignation, the Vice President shall become President.
Once Ford became President he nominated Nelson Rockefeller as Vice President and his nomination was also confirmed by Congress.
When everything was said and done we ended up with both a President and a Vice President that were ‘appointed’ rather than elected to their respective offices. Ford and Rockefeller remained in office for the balance of the Nixon term (3 plus years). At the end of the term Ford ran for re-election and lost to Jimmy Carter, while Nelson Rockefeller did not run as VP and dropped out of politics.