Newark Mayor Cory Booker announced today that he will seek the Senate seat made vacant when Sen. Frank Lautenberg, D-N.J., died earlier this week.

"I'm here today to officially announce my candidacy to be New Jersey's next United States senator," Booker said in a news conference in Trenton, N.J. "Democracy is not a spectator sport, but now as much as in any time, we must bring people together. We must actually get into the complicated difficult messy arena and take on the difficult challenges, work in uncommon ways with conviction and courage."

Booker, who has served as mayor of Newark for seven years, praised Lautenberg for his service and leadership in New Jersey and the Senate.

"As a senator and as a citizen, he has been one of the most impactful New Jerseyans. He was truly a giant in the United States Senate. He was a giant for our state and a giant for our nation from his service in World War II to his assiduous work and advocacy in the U.S. Senate," he said. "Generations yet unborn will feel the impact of his leadership and contributions."

New Jersey Gov. Chris Christie set the date for the special election to fill Lautenberg's seat for Oct. 16, three weeks before Christie faces re-election himself. On Thursday, Christie appointed state Attorney General Jeff Chiesa, a Republican, as interim senator, but Chiesa does not plan on running in the special election this year. The Democratic primary for the seat will be held in August.

Booker, 44, is well known for his heroic acts as well as for his active Twitter account. He said today he's often been criticized for his tweeting, but that will not deter him.

"Too much Twitter from the mayor, too much exposure - there is not a criticism I haven't heard over the years. I've heard it all but, there's one thing that everyone has to admit about my life as a professional," he said. "I do not run from challenges. I run towards them."