Chris Christie has appointed NJ Attorney General Jeff Chiesa as the interim replacement for Sen Lautenberg’s seat. The two have a long history together. From Chiesa’s Wikipedia Bio:
In 1988, Chiesa joined the Cranford law firm of Dughi, Hewit & Palatucci (now known as Dughi & Hewit). There he met Chris Christie, who had joined the firm in 1987.
In 2002, he followed Christie to the office of the United States Attorney for the District of New Jersey …
In 2009, after Christie was elected Governor of New Jersey, Chiesa headed his transition team. Christie then named Chiesa his chief counsel.[2] He served in this position until being nominated by Christie to succeed Paula Dow as Attorney General on December 12, 2011.
Here’s his Offical Bio on the State of NJ Website.