Thanks to Booker's national profile and prodigious Twitter following, the event attracted many reporters. And although Booker did most of the talking, it was a big moment for the little-known, longtime central Jersey legislator: She saw more cameras Tuesday than she has at any campaign stop so far.
Booker and Buono, both of whom have worked as attorneys, first stopped at a law firm to talk about taxes, the effect of the economy on business, and immigration.
Booker said to the lawyers: "I'm glad you got a chance to meet the next governor of the state of New Jersey."
They then moved on to a realty office and a tuxedo shop where Booker used to buy his threads. Buono pushed her case at each stop, saying New Jersey is in far worse shape than Christie would have you believe. "There's a malaise; there's a certain anxiety that the New Jersey they grew up in is slipping away," she said.
But Booker still stood out. He is more than a head taller than his Democratic counterpart, and he repeatedly showed off his prowess speaking Spanish. He was asked - and answered - most of the questions at the news conference in the back of the Andros Diner, and he went on tangents about his successes in Newark.
Booker's support was unequivocal. He cited Buono's "real vision for cities" and insinuated that he may not have had to lay off police officers if she were governor.
"We would have figured out a way," Buono said.
Booker said that if voters, even moderate Republicans, looked past Christie's likability and examined the issues, they would find themselves agreeing with Buono. He cited her support for a greenhouse gas treaty and gay marriage; he noted that Christie defunded Planned Parenthood, a tax cut for the working poor, and a public transit tunnel into New York City.
But Booker also repeatedly brought up his friendship with Christie, with whom he filmed a parody video last year. Booker said he liked the Christie kids and even praised the governor for the "beautiful moment" when he embraced President Obama after Hurricane Sandy.
"I have a lot of affection for Chris Christie; I worked closely with him as mayor," Booker said.
Booker has strenuously supported several of Christie's biggest issues: Pension and benefit reform for public employees (which Buono opposed), the reorganization of the higher education system, a cap on property tax increases, and school reform in Newark.
That point wasn't lost on Michael DuHaime, Christie's campaign adviser, who said, "On issues of most importance to New Jersey voters, Mayor Booker has stood with Gov. Christie time and time again - showing Republicans and Democrats can work together."
Booker acknowledged that he and Christie have had a "very robust and vibrant partnership" on educational issues, and he supports Christie's plan to give students in failing districts vouchers to attend elsewhere, while Buono doesn't.
But he opposes Christie on school funding, school construction, and higher education affordability.
Prominently supporting Buono serves to boost Booker's bona fides among loyal Democrats and could repair relations with party stalwarts in advance of a possible U.S. Senate run.
Buono, meanwhile, faces an opponent with millions more dollars and high approval ratings. But the state is still blue, and Christie's poll numbers have inched downward since the aftermath of Sandy.
And now, Buono has a big-name Democrat willing to help her out. "I will raise money for her," Booker declared Tuesday.
"Ya hear that?" Buono said, smiling.
Contact Matt Katz at 609-217-8355, firstname.lastname@example.org, or @mattkatz00. Read his blog, "Christie Chronicles," at philly.com/christiechronicles