New Jersey Gov. Chris Christie delivers his inaugural address after being sworn in for his second term on Jan. 21, 2014 at the War Memorial in Trenton, N.J. (Jeff Zelevansky/Getty Images)

New Jersey state lawmakers voted Monday to combine their investigations into Gov. Chris Christie's (R) administration, creating a special joint committee.

Previously, the matter had been handled separately by the state Assembly and the state Senate, which have been investigating the matter independently of the U.S. attorney office's inquiry.

Democratic leaders announced last week that they would combine their efforts, but they first needed lawmakers to sign off on it -- something both the the Assembly and the Senate did Monday.

Leading the 12-member special joint committee will be Assemblyman John Wisniewski (D) and Sen. Loretta Weinberg (D), who had been leading their chambers' respective efforts. Four of the 12 members on the panel are Republicans.

"Based on the expert advice of our special counsel, the optimal way to proceed is to streamline the legislative investigations and make clear to everyone that we expect full cooperation and responsiveness as this inquiry proceeds,” state Assembly Speaker Vincent Prieto (D) said. “This is the best way to ensure that the people of New Jersey get the answers they need to these questions about the abuse of government power.”

A member of Christie's office and Christie appointees at the Port Authority of New York and New Jersey have been implicated in a plot to create a traffic jam in Fort Lee, N.J., which Democrats allege was politically motivated. Christie has said he had no knowledge of the plot.