Democrats in the New Jersey state Assembly have decided to launch a special investigative committee to question more members of the Christie administration about the bridge closures in Fort Lee, N.J., according to two Democratic aides.

"It will look into a wide variety of issues related to the closures and Gov. Chris Christie's staff," an aide said, speaking on the condition of anonymity to discuss internal decisions. "There is a need to focus on a broad array of issues and the Assembly is going to dedicate itself to finding the truth beyond the usual committee process."

A second aide said forming a "special investigative committee" was "now a top priority," especially after David Wildstein, a former Port Authority official in the Christie administration, declined to answer questions last week at an Assembly hearing about his involvement in the scandal.

The committee will be chaired by Assemblyman John Wisniewski, chairman of the transportation committee. The aides added that Wisniewski plans to renew and expand the legislature's subpoena powers. Wisnieski said he expects to subpoena Christie's former campaign manager Bill Stepien and his former deputy chief of staff Bridget Kelly, adding that his investigation will "follow trail into the governor's office" and look into "all emails and documents."

"We are likely going to hear testimony from Bridget Kelly and Bill Stepien as part of this special investigative committee," he said.

Christie last week dismissed Kelly and Stepien after emails and texts indicated that they orchestrated a multiday traffic jam in an act of political retaliation. The scandal has become an early test for Christie on the way to a possible presidential run in 2016.

"The evidence that has come out in recent weeks makes clear that this now goes above and beyond a transportation issue and goes into the highest ranks of the executive branch," Wisniewski said in a statement. "A concerted and focused investigation with increased resources is now needed."

Assembly Democrats agreed to move forward with the investigative committee on Monday morning during a closed-door meeting at the state capitol.

Democrats in the state senate also have called for further investigations. State Sen. Loretta Weinberg, in a statement Monday afternoon, asked for a "joint legislative committee," signaling the Senate's intentions to work alongside Wisniewski.

"The issue has grown and the unanswered questions have multiplied," said Weinberg. “This involves the abuse of power, risks to public safety, harm to interstate commerce and a possible cover-up. We need to combine the resources of both houses of the Legislature to get to the full truth. Senate President Sweeney and I will work with the Assembly leadership to form a joint committee in the new legislative session to pursue all aspects of this case.”

Wisniewski will make a formal announcement of his plans this afternoon and will hold a press conference.

"As the evidence in the case has unfolded, it's become clear the questions that need answering here are no longer just transportation questions," Speaker-elect Vincent Prieto, also a Democrat, said in a statement. "They are now much bigger than that, and we need a super committee led by Asm. Wisniewski armed with the resources he needs to build upon his progress and ensure all questions are answered. "