The Democrat that many thought would challenge Gov. Chris Christie, says he plans not to. Newark Mayor Cory Booker announced on Thursday he would explore a potential Senate run in 2014. U.S. Senator Frank Lautenberg would be up for reelection then. Booker said he would talk to Lautenberg before making a final decision. As of right now, State Senator Barbara Buono is the only one running for governor as a Democrat.