The Journal cites three sources familiar with Booker's conversations, who told the newspaper that although Booker is leaning toward a Senate run, he "has been talking about the governor's race with strategists both steeped in New Jersey politics and independent from it, and he could change his mind at the last minute and still run for the state's powerful executive position next year."

But running for Senate could be complicated for the mayor as well, as Lautenberg, the incumbent Democrat, has not yet announced his plans for 2014. He'll be 90 years old on Election Day and is considered one of a handful of long-serving Democrats likely to announce their retirement before 2014, though he has thus far given no indication he won't be running to keep his seat.

However, a recent poll gave Booker a wide lead over Lautenberg, with 59 percent support to Lautenberg's 22 percent. Though nearly two-thirds of New Jersey Democratic voters approve of the senator's job performance, only about half that believe he should seek reelection in 2014.

And in a primary match-up against Lautenberg, Booker would be able to mitigate the typical advantage of incumbency: Deep campaign coffers. His national profile and connections would make it easier for the mayor to raise the funds needed to take down an incumbent.