U.S. Vice President Joe Biden swore in Democratic Senator Patrick Leahy of Vermont Tuesday as president pro tempore of the Senate. Leahy is now the longest-serving Democrat in the Senate and moves to third place in the line of presidential succession, behind Biden and Speaker of the House of Representatives John Boehner. Leahy succeeded Hawaii Democratic Senator Daniel Inouye, who died Monday at the age of 88. He is also in line to succeed Inouye as chairman of the Senate Appropriations Committee.