Final answer:
If the vice presidency of the United States is vacated, the president must nominate a new vice president who will assume the responsibilities and duties of the office upon confirmation by Congress.
Step-by-step explanation:
According to the Constitution, if the vice presidency of the United States is vacated, the president must nominate a new vice president. This nomination must be confirmed by a majority vote of both Houses of Congress. Once the new vice president is confirmed, they will take office and assume the responsibilities and duties of the vice presidency.