TRENTON, N.J. — Cory Booker, the mayor of Newark and perhaps New Jersey’s highest-profile Democrat, has ruled out a bid for governor next year and is interested in a run for Senate in 2014.

The decision, announced Thursday on Twitter, means Booker has decided against a possible campaign against Governor Chris Christie, a Republican. But depending on how things play out, he could find himself in a Democratic primary race against Senator Frank Lautenberg, who is 88 and declined to talk about his political future on Thursday.