Newark Mayor Cory Booker is floating the possibility of a challenge to Gov. Chris Christie (R-N.J.), according to a post by NJPoliticker's Max Pizarro:

Newark Mayor Cory Booker and his political consultant Mark Matzen are meeting face-to-face with county chairs and making it known that Booker is weighing a run for governor and plans to decide by December, according to party sources. [...]

Another party source said as Democrats get closer to the national convention and Christie grabs headlines as the imminent keynoter at next week’s Republican confab in Tampa, national Democrats are alert to recruiting a counterpoint – someone who can present more than token opposition in next year’s gubernatorial contest.

Booker was just announced as a speaker at the Democratic National Convention. He has a warm relationship with the governor; if he does run against Christie, this Seinfeld parody they did together will surely get a lot of play.