When the vice president is absent who takes his place in the senate?

In the absence of Vice President the speaker of the house should resides. The Speaker of the House is the presiding officer of the United States House of Representatives.  The Speaker is second in the United States presidential line of succession, after the Vice President and ahead of the President pro tempore of the U.S. Senate. In the United States, the Speaker of the House is a leadership position and the office holder who actively works to set the majority party's legislative agenda.