The subpoenas were sent to three organizations and 17 individuals, said the chairman of the committee, Democratic Assemblyman John Wisnieswki. He declined to identify the recipients before they were served, CNN reported.
New Jersey Gov. Chris Christie's ex-top aide Bridget Anne Kelly, 41, was among those likely to be subpoenaed, said state Senate Majority Leader Loretta Weinberg, a Democrat from Teaneck. Kelly's eight-word August email saying "Time for some traffic problems in Fort Lee" was followed in September by four days of gridlock at the George Washington Bridge.
Christie fired Kelly last week after emails and texts detailed she helped orchestrate the apparent revenge lane closings that created the colossal backup on the world's busiest motor-vehicle bridge, which connects Fort Lee, N.J., and New York City.
The motive for the closures was unclear. There has been speculation it was a case of political retribution against Christie's opponents, in particular Democratic Fort Lee Mayor Mark Sokolich, for not endorsing Republican Christie for re-election in last year's gubernatorial race.
Weinberg was the Democratic lieutenant governor nominee on the ticket that lost to Christie in his first win as governor in 2009. Weinberg ran with Gov. Jon Corzine, who lost to Christie and running mate Kim Guadagno.
Weinberg, expected to be chairwoman of the Senate's investigative committee, said she believed the panel's political makeup should be three Democrats and two Republicans, USA Today said.
The state Assembly, conducting a separate inquiry into the bridge scandal, was also expected to issue subpoenas Thursday, after the lower chamber votes to extend its investigation in the new legislative session, said Democratic Assemblyman John Wisniewski of Middlesex.
Wisniewski, expected to head the lower chamber's investigative panel, declined to say whether Kelly and fired Christie campaign manager and senior aide Bill Stepien, 36, would be targets of the Assembly's Thursday subpoenas.
Christie fired Stepien along with Kelly last week for what Christie said was Stepien's poor judgment in discussions about the closings as they started to become a political issue.
At one point Stepien assured David Wildstein -- a Christie appointee to the Port Authority of New York and New Jersey who ordered the lane closures -- the traffic havoc wasn't a real cause for concern.
"Ultimately, not an awful story," Stepien wrote.
The Port Authority runs the bridge.
Stepien has hired a lawyer to represent him in the investigation, Leon Sokol, the attorney for the Assembly transportation committee that led the initial probe of the lane closures, told the Wall Street Journal.
Former assistant U.S. Attorney Reid Schar, the federal prosecutor who helped convict former Illinois Gov. Rod Blagojevich of corruption, will advise the Assembly panel, Wisniewski said.
"There are a lot of legal issues that we need to understand and work through very carefully," he told reporters Wednesday. "We wanted to have the right guidance, and Reid Schar brings his experience as an Assistant U.S. attorney -- somebody who's been involved in complicated investigations."
No evidence points directly to Christie, Wisniewski said.
But "an investigation into the finances of the Port Authority [of New York and New Jersey] ... has now led us to the governor's office," he said.
Christie is a possible 2016 Republican presidential hopeful.
In addition to the parallel legislative investigations, the U.S. attorney's office is also probing the incident.
Democratic New Jersey state Sen. Raymond Lesniak of Elizabeth said he would ask the Manhattan district attorney in New York to investigate possible violations of New York state laws.