The Vice President of the United States is assigned the responsibility of presiding over the Senate and designated as its president by the United States Constitution. The vice president, as President of the Senate, has the authority (ex officio, for he or she is not an elected member of the Senate) to cast a tie - breaking vote. Other than this, the rules of the Senate grant its president very little power (in contrast to the powerful office of Speaker of the House of Representatives).
who acts as the president of the senate
The Vice President of the United States