Byrd was 92, and had served in the Senate for just over half a century, the longest of any individual in its 207 year history.
Lautenberg, 86, has been elected five times to the upper house of the Congress, although he retired once, in 2000, and then came out of retirement to run again in 2002.
That was the year of the so-called 'Torricelli Switcheroo,' when then-Senator Robert Torricelli dropped out of his re-election race after a rapid drop in the polls because of ethics allegations made against him.
On an early October evening a month before election day, Democratic party leaders huddled in Trenton and at the Governor's mansion in Princeton to try to decide who to pick as Torricelli's replacement.
Former Senator Bill Bradley was considered, and reportedly an offer was actually made to U.S. Representative Frank Pallone(D-Monmouth) who turned it down for personal reasons before Lautenberg was asked if he would take on the job.
After surviving a court challenge by Republicans, Lautenberg went on to overcome the polling lead of Republican Doug Forrester in a matter of just four weeks and win election to what was then his fourth term in the Senate.
This year, Lautenberg was diagnosed with stomach cancer, but just this past weekend announced at a dinner of Garden State Equality that he is now "cancer free," with his doctors last week telling him his cancer is in remission after aggressive treatment at Sloan Kettering.
Today, he paid respects to his Byrd, saying " We loved him, we miss, and I take no joy in becoming the oldest Senator. Obviously if I had my choice I'd be the youngest."
Asked repeatedly in the past if he would consider running for re-election in 2014, when he would be 90 years old, Lautenberg said "Who knows? I feel good, I feel vigorous. We'll have to determine useful ability but now I love my job."
Considered one of the most liberal members of the Senate, one of his signature moments came in the 1980's when he wrote the legislation that would lead to the banning of smoking on all domestic airline flights.
Folow Brian Thompson on Twitter @brian4NY