Politics watchers are expecting an especially low turnout in the primaries, which will pick a Democrat and Republican to campaign for the unfinished term of Lautenberg, who died in June. Democratic Newark Mayor Cory Booker and Republican former Bogota Mayor Steve Lonegan are the clear front-runners.
A mere 200,000 or fewer voters could decide the unprecedented mid-August primaries. The victors will square off in an Oct. 16 special election, and the winner will head to Washington for 15 months to finish out the term but would have to campaign again next year for a full six-year Senate term.
Booker, 44, began the race with obvious advantages over three opponents, U.S. Reps. Frank Pallone and Rush Holt, and Assembly Speaker Sheila Oliver. Booker is nationally known, well-financed and has celebrity friends who have raised his profile and helped raise money. Such leverage is hard to overcome, particularly in a nine-week campaign.
Booker's personal finances have recently become a target as questions were raised about his stake in the social media company Waywire, which he co-founded, and severance payments from a former law firm, which he received through 2011 while the firm had business with city agencies under his control.
The two veteran congressmen, Pallone and Holt, are in the race at a time of historically low public confidence in Congress. Both are known as champions of public education and the environment, but the state's largest unions and environmental groups stayed neutral rather than pick one over the other. The Lautenberg family endorsed Pallone, while the National Organization for Women endorsed Holt.
The only woman in the Democratic primary, Oliver based her campaign on the need for more female representation in Congress. She would be the only woman in New Jersey's 14-member congressional delegation. But she hasn't developed the donor network or get-out-the-vote operation that help win elections and has hinted that this race could be a trial run for next year's Senate campaign.
Like Booker, Lonegan, 57, has already defined himself politically. He is the veteran of two failed gubernatorial primaries and a 1998 congressional race who can count on money from the anti-tax group Americans for Prosperity and from others with conservative agendas. He resigned as state director of AFP to run for Senate.
Lonegan was criticized last week for a social media post that some said was offensive. The tweet said: "Just leaked - Cory Booker's foreign policy debate prep notes." It showed a map labeling parts of Newark "West Africa, Guyana, Portugal, Brazil" and other nations including Afghanistan and Pakistan.
Newark is a largely minority city whose residents have roots in many parts of the world. The post was removed.
Lonegan's only challenge comes from a political unknown, Somerset County physician Alieta Eck, another tea party candidate with a small budget who is in her first campaign for public office.