Wheelchair-bound, he received warm greetings from several colleagues on the Senate floor. He also voted to move along the nomination of a new EPA commissioner, Gina McCarthy.
"Frank was a passionate public servant who was not afraid to fight and vote for what he believed in. He loved the Senate," said Sen. Patty Murray, D-Wash. "He retired once but service called him back, and until the very end of his life, Frank made the trip from New Jersey to D.C. to fight for the issues he believed in and the people he represented. He gave everything he had to public service."
Along with Lautenberg's legislative accomplishments, he had a string of electoral coups, including an upset over Republican Rep. Millicent Fenwick in his first race for Senate, and a victory in a strange, abbreviated, back-from-retirement campaign 20 years later.
He initially retired in 2000 after 18 years in the Senate, saying he did not have the drive to raise money for a fourth campaign. He served on the boards of three companies, two graduate schools and the US Holocaust Memorial Museum.
But New Jersey Democrats recruited Lautenberg out of retirement in September 2002 as an 11th-hour replacement for Robert Torricelli, Lautenberg's longtime rival, who had abandoned his re-election bid just five weeks before Election Day.
Republicans went to court to prevent what they called the Democratic Party's ballot "switcheroo." When that failed, they attacked Lautenberg as a political relic ill-suited for dangerous times.
But Lautenberg surged to an easy win over Republican Douglas Forrester and returned to the Senate in 2003 at age 78, resuming his role as a leading liberal, and he made it clear that his return to office was no mere cameo.
When Democrats regained a Senate majority in 2007, he returned to the powerful Appropriations Committee, on which he had served for 15 years.
At age 84, he beat back a Democratic primary challenge in 2008 and went on to another easy win in the November general election. It made him the first New Jersey person ever elected to five Senate terms.