Before Republicans won control of the Senate in the 1994 elections, Lautenberg was chairman of key subcommittees responsible for transportation appropriations and the Superfund pollution cleanup program. He became the ranking Democrat on those panels after 1994.
From those posts, he worked to secure hundreds of millions of dollars for mass transit projects in the state, which he said would reduce pollution and traffic congestion. He also was a leading defender of Amtrak, the nation's passenger rail system.
In 1984, as a novice lawmaker and member of the minority chamber in the Senate, Lautenberg wrote a bill to withhold federal highway funds from states that did not set 21 as a minimum age to buy and possess alcohol.
After the federal voting age was lowered to 18 in 1971, many states followed suit by setting minimum drinking ages at 18 to 20.
By the early 1980s, the problem of drunken driving by teenagers was getting widespread attention. Reagan signed the bill, and by 1988, every state had a legal drinking age of 21.
Lautenberg often attacked tobacco companies' advertising tactics. During a 1989 debate over smoking, when tobacco-state lawmakers asked what would become of tobacco farmers, Lautenberg scoffed, "Grow soybeans or something."
Another frequent target was the gun industry. "Common sense tells you that there are more than enough dangerous weapons on the streets," said Lautenberg, who sponsored numerous gun-control measures, a few of which were enacted.
He also spent much of his political career pushing for funding for Superfund, a program that pays for cleanup of environmentally hazardous sites.
Lautenberg was a reliable vote for traditional Democratic policies, though he bucked President Bill Clinton in 1993 on the budget because he said it raised taxes and didn't cut spending enough. He also voted against Clinton on the North American Free Trade Agreement, opposed by the staunch labor allies Lautenberg had come to depend on.
Later in his career, he became a foil for Christie.
In 2012, Christie called Lautenberg a "partisan hack" and an "embarrassment" and said it was time for him to retire. Lautenberg called Christie "the name-calling governor" and, in one speech, "the king of liars."
Lautenberg had health problems in recent years. He had the flu and missed the Senate's Jan. 1 vote to avoid the so-called fiscal cliff of rising taxes and falling government spending, then missed several votes two months later because of leg pain. A chest cold kept him from attending a May 29 tribute in New York honoring him for his contributions to the Jewish community and Israel.
He had been diagnosed in February 2010 with B-cell lymphoma of the stomach and underwent chemotherapy treatments until he was declared in June 2010 to be free of cancer. He worked between the treatments.
The diagnosis came just days after the death of Sen. Robert Byrd of West Virginia, making Lautenberg the oldest member of the Senate.
For his first 14 years in the Senate, he was often in the shadow of New Jersey's other, better known senator, Bill Bradley, a former pro basketball player and 2000 presidential candidate. But he proved a formidable and bruising foe.
Running for an open Senate seat in 1982, Lautenberg won 51 percent of the vote against Fenwick. The win, financed largely with $3 million of Lautenberg's own fortune, was a shocker.
Fenwick was 72 when Lautenberg questioned her capacity to serve in the Senate. On the campaign trail, he criticized her "capability" to be a senator, but some observers seemed to think he was going after her age — a fact that was noted 26 years later when he ran for re-election at age 84.
"It's hard when your own words come back to haunt you, isn't it, Mr. Lautenberg?" said an ad for his Democratic primary opponent, U.S. Rep. Robert Andrews, whom he defeated handily before beating former U.S. Rep. Dick Zimmer in the general election.
After Lautenberg won the 1982 election, Nicholas Brady, who had been appointed to serve the remainder of the previous term, resigned early to give Lautenberg valuable seniority over other new senators. He was sworn in Dec. 27, 1982, by a federal judge from Denver while he was vacationing in Vail, Colo.
In 1988, Lautenberg faced Pete Dawkins, a handsome Heisman Trophy winner who attended the U.S. Military Academy and went on to become a brigadier general and successful executive. Lautenberg's campaign assailed Dawkins as an out-of-touch carpetbagger and ran ads urging Dawkins, "Be Real, Pete." Lautenberg won with 54 percent of the vote.
He won a third term in 1994 against Republican Garabed "Chuck" Haytaian, despite the GOP gains nationwide that overturned Democratic majorities in the Senate and House and Haytaian's criticism of Lautenberg as a "silent senator."
In his unusual five-week return to campaigning in 2002, Lautenberg persevered with a steady, risk-averse campaign that portrayed him as a "serious senator" for "serious times" a year after the 9/11 terrorist attacks.
Republicans focused on Lautenberg's liberal voting record, notably his opposition to the death penalty, development of a missile defense system and the 1991 resolution authorizing force against Iraq.
Born in urban Paterson, N.J., the son of Polish and Russian Jewish immigrants, Lautenberg never forgot his roots. He often recounted what government did for him — and what it could have done to help his widowed mother as she struggled to pay his father's medical bills.
"We want to help. That's government's role," Lautenberg said during his successful bid for re-election in 1994.