Patrick Leahy sworn in as Senate Pro Tempore after death of Daniel Inouye

Sen. Patrick Leahy, a Democrat from Vermont, was sworn in on Tuesday as President pro tempore of the United States Senate following the death of Sen. Daniel K. Inouye of Hawaii on Monday.

Vice President Joseph Biden administered the oath, the Washington Post reported.

"Kind of a bittersweet moment,” Biden said to the room full of senators gathered for the occasion, Politico reported.

The title is given to the "most senior member of the chamber's majority party" according to the Post. Leahy is 72 years old and began serving in the Senate back in 1974. He currently chairs the Senate Judiciary Committee.

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As Politico noted, Leahy is now third in line to be president of the United States.

“I can’t tell you how much it pains me," Leahy said before taking the oath. "[Inouye] was one of the greatest members of this body ever to have served, and a dear friend to so many of us… He’s perhaps the best role model for public service any American could ask for.”