Booker announced his intentions to "explore" a U.S. Senate run in an op-ed published in the Star-Ledger Thursday.
"Let there be no doubt, I will complete my full second term as mayor," Booker wrote. "As for my political future, I will explore the possibility of running for The United States Senate in 2014."
But Booker may be farther along in the decision-making process than his talk of "exploring" a run suggests. "The mayor intends to be a candidate," the adviser told TPM.
As for Lautenberg, the adviser said Booker has tried to reach out to him but has so far been unable to connect with the 88-year-old senator, who was first elected in 1982. Speculation that Lautenberg's age could keep him from seeking another term has been tempered by reports that Lautenberg is interested in another run.
Booker has reached out to Lautenberg "a number of times over the past week or so," according to the adviser and Team Booker has "no insight" into Lautenberg's intentions, the adviser said.
"We want to give him every courtesy that we can," the adviser said. "The mayor does respect him as a leader of New Jersey and the Democratic Party."
As for Booker, he intends to run as "the champion of urban issues," according to the adviser, taking lessons from his terms as Newark's mayor to the national stage. In his op-ed, Booker highlighted accomplishments he says have improved things in New Jersey's largest city.
Booker would likely have a broad base of national support, thanks in part to his image as the Twitter-friendly hands-on city leader known for living a week on food stamps and rescuing a neighbor from a burning building. The New York Times reported last week his national profile has rankled some Democrats in the state, but there's little doubt that his semi-celebrity status would be a boon to fundraising and draw attention to his candidacy.
The adviser declined to characterize conversations Booker may have had with national Democratic leaders in the run-up to Thursday's announcement, but BuzzFeed reported that a "senior New Jersey official" said the White House urged Booker to run for the Senate seat instead of against Gov. Chris Christie (R). Senate Majority Leader Harry Reid (D-NV) told Politico that Booker "would be a wonderful senator," though he noted that "of course we have to work out a few issues." Reid has indicated he will back Lautenberg if he runs again.