"He never quit anything. He never gave up. He never gave in," Vice President Joe Biden told the 1,100 mourners, including former Secretary of State Hillary Rodham Clinton, New Jersey Gov. Chris Christie and several former governors and many of Lautenberg's Senate colleagues.
Lautenberg, a liberal Democrat from New Jersey, died Monday after suffering complications from viral pneumonia. At 89, he was the oldest member of the Senate and the last of 115 World War II veterans to serve there.
In a service that spanned two and a half hours, admirers including Clinton and several of Lautenberg's children and grandchildren remembered the causes he championed and his drive to fight for what he believed, whether on the Senate floor or around the dinner table. They also recalled him as someone who never forgot the roots from which he rose or lost sight of others still striving to achieve.
Lautenberg was "the living definition of what it means to be a successful man," said Biden, who counted Lautenberg as one of his closest friends in the Senate during the more than a quarter-century they served together.
Lautenberg repeatedly sought Biden's advice on whether to run for re-election next year before Lautenberg ultimately decided he would not, though "he desperately, desperately, wanted to run again," the vice president said.
Lautenberg "always had to be in the game," Biden said. "Too much left to be done ... too many injustices left to right. Too many people needing help."
Born to an immigrant family in Paterson, N.J., "Frank would always be a man of the people and for the people, never forgetting his humble start," Rabbi Elliot Cosgrove said.
Reflecting on such signature Lautenberg accomplishments as laws that banned smoking on most U.S. flights and made 21 the drinking age in all 50 states, Cosgrove recalled the criticism the senator withstood over matters that "in retrospect, appear as inevitable and obvious as they seem necessary."
Not everyone was a fan of the increase in the drinking age, of course. Lautenberg's daughter Lisa Lautenberg Birer, who lost her voice and had her speech read by her own daughter, joked that she lost 300 friends in college because "Dad raised the drinking age."
She also noted that his toughness and persistence weren't limited to Senate negotiations. Her father once fell 1,000 feet down a ski slope, sat up with a broken collarbone and refused to wait for the ski patrol, she said.
"Frank was the most positive person I know," said his wife, Bonnie Englebardt Lautenberg.
U.S. Sen. Robert Menendez of New Jersey called Lautenberg the most tenacious man he'd ever met. Lautenberg's story "was an American story, but in his heart and for his lifetime, he was a man from New Jersey, a kid from Paterson," Menendez said.
Clinton praised Lautenberg's advocacy on matters including from chemical safety, gun control, mass transportation, making planes smoke-free, higher education for veterans and helping New Jersey residents trying to build businesses.
"There was never any doubt where he stood," said Clinton, who also described going with him in 1999, when she was first lady, to meet a planeload of Kosovar refugees. He hugged the new arrivals and talked to them about his own forebears' arrival, she recalled.
"Here he was again, representing the best of who we are as Americans," Clinton said.
"America the Beautiful" played as Lautenberg's flag-draped casket was carried from the synagogue.
His body was taken to the train station in Secaucus, N.J., which is named for him. An honor guard of drums and bagpipes performed "God Bless America" and taps before a brief service there. The casket was sent from there to Washington by a private Amtrak train.
Lautenberg was an ardent defender of Amtrak and worked to secure hundreds of millions of dollars for mass transit projects.
His casket was set to arrive at the U.S. Capitol on Thursday and lie in repose in the Senate chamber, on the Lincoln Catafalque, a bier that was built for the coffin of Abraham Lincoln.
Lautenberg, who served in the Army Signal Corps during World War II, will be buried Friday at Arlington National Cemetery.
A multimillionaire businessman, Lautenberg was first elected to the Senate in 1982 and went on to serve nearly 30 years there in two stints.
Lautenberg's second daughter, Nan Morgart, said that during her father's brief retirement from the Senate, "he was so bored" that he'd call her daily to ask how many products she'd sold at her job as a sales representative for IBM.
Lautenberg won his last race in 2008 at age 84, becoming the first New Jersey politician ever elected to five Senate terms.
Lautenberg's eldest daughter, Ellen, said her father's life story "shaped my path by demonstrating that there are always new opportunities to learn and grow."
Associated Press writer Jennifer Peltz contributed to this report.