Final answer:
The official president of the Senate is the Vice President, who presides over the Senate and can vote in the event of a tie. The President pro tempore is an officer chosen by the Senate and fills in for the Vice President when necessary.
Step-by-step explanation:
The official president of the Senate in the United States is the Vice President. The Vice President is the presiding officer of the Senate and has the authority to cast a vote in the event of a tie. The Vice President, in this role, ensures that Senate proceedings are conducted effectively and efficiently.
The President pro tempore is another officer chosen by the Senate. This position is usually held by a senior senator of the majority party and serves as the presiding officer when the Vice President is not available. The President pro tempore is also in line of succession for the presidency in case of vacancies.