With the death of Robert Byrd, the presidential line of succession has changed. Hawaii Democratic Sen. Daniel Inouye will more than likely be the new Senate president pro-tempore.
Byrd, as the most senior member of the party holding the majority, served in the role of president pro-tempore. Under the Presidential Succession Act, that position is third in line to succeed the president: vice president, House speaker, and then president pro-tempore.
Senate tradition is for the majority party to elect its most senior member to the position. If that tradition continues today, Inouye is next is line. If Inouye declines to serve, Vermont Sen. Pat Leahy (D) is next in seniority.
*** UPDATE *** Shortly after the Senate opens today's session at 2:00 pm ET, Sen. Inouye will be sworn in as the new Senate president pro tempore, replacing Byrd according to a leadership aide.