Newark Mayor Cory Booker is officially a candidate for U.S. Senate in New Jersey.
The 44-year-old Democrat made his candidacy official at a news conference Saturday in New Jersey's largest city.
Booker was joined by former U.S. Sen. Bill Bradley, a former pro basketball player who for 18 years held the seat Booker is seeking.
Booker is also holding an event in South Jersey later Saturday.
The seat became vacant with the death of the country's oldest senator, Frank Lautenberg, on Monday.
Reps. Frank Pallone and Rush Holt are also planning to enter the Democratic primary, which will be held in August. Booker is considered the early front-runner.
Candidates have until Monday afternoon to enter the race to fill the seat for the rest of the term, which ends in 2014.