FILE - In this May 21, 2013 file photo, Sen. Orrin Hatch of Utah listens on Capitol Hill in Washington. Republican senators poised to lead major committees when the GOP takes charge are intent on pushing back many of President Barack Obama's policies, setting up potential showdowns over environmental rules, financial regulations and national security. (AP Photo/Charles Dharapak, File)
Utah Republican Sen. Orrin Hatch has been sworn in as president pro tempore of the U.S. Senate.
Hatch's ascension to the role around 1 p.m. ET Tuesday makes him third in the line of presidential succession behind Vice President Joe Biden and House Speaker John Boehner
He succeeds Democratic Sen. Pat Leahy of Vermont in the role.
The 80-year-old Hatch has served as a senator since 1977 and is the longest-serving Republican in the Senate.
Hatch also will serve as chairman of the tax-writing Senate Finance Committee in the newly Republican-controlled U.S. Senate.