Sen. Daniel Inouye of Hawaii is to be sworn in as President Pro Tem of the U.S. Senate--third in line for the presidency--at 2 p.m. Monday.

The 47 1/2 year veteran Senate Democrat is chairman of the Senate Appropriations Committee, and earlier this month became the second longest serving U. S. senator in history--behind only Sen. Robert Byrd, who died Monday.

He will become third in line for succession to the presidency, after Vice President Joseph Biden and House Speaker Nancy Pelosi.

Inouye remembered his longtime colleague, Byrd, in a statement:

“My heart is heavy with sadness following the passing of a dear friend, Robert C. Byrd, Senator from West Virginia.

"We have been friends for nearly 50 years and I am overcome with memories.  Nearly 48 years ago Senator Byrd was one of the first to greet me in the chamber of the United States Senate. 

"Since that first moment of friendship we have worked together on many projects.  And since those early days, I have called him, ‘my leader.’ He was my mentor.  Over the years he provided me countless opportunities and tasked me with positions of critical national oversight while guiding my actions with the temperance he learned as the longest serving Senator in history."