Booker, who served for seven years as mayor and used his national profile to help attract billions of dollars in investment to Newark, about 12 miles from New York City, is now a U.S. Senator. He won a special election last October to succeed Senator Frank Lautenberg, who died in office.
Former City Council President Luis Quintana has held the interim mayorship.
The two Democratic candidates vying for the job are Shavar Jeffries, 39, a former assistant attorney general and a civil rights lawyer, and Ras Baraka, 44, a high school principal, city councilman and the son of the late activist and poet Amiri Baraka.
In this heavily liberal city, a Democrat is virtually guaranteed victory.
