Answer:
President pro tem
Step-by-step explanation:
Most business in the Senate is presided over by a president pro tempore (pro tem). Elected by the senators, by custom, the pro tem is the longest serving senator in the majority party. The pro tem acts in place of the vice president, who is president of the Senate. The vice president normally presides over Senate meetings only on ceremonial occasions or when the vote is likely to result in a tie, and the vice president votes only if there’s a tie.