Cory Booker prepping for Joe Biden standoff at debate

This is “new territory” for Booker, said Patrick Murray, director of the Monmouth University Polling Institute, which is based in Booker’s home state of New Jersey.

“It’s not clear that it’s actually going to be productive,” Murray said. “That’s not simply because it undermines his brand identity as a positive person, but it doesn’t look like it’s having an impact with the voters you need to sway.”

For months, Booker has professed to be satisfied with being a tortoise among hares — and, until recently, he regularly passed up opportunities to draw explicit contrasts with or criticize his rivals, including Biden.

“I plan on focusing on my record.”

Underpinning Booker’s rhetorical shift is an implicit appeal to Democratic voters, particularly African Americans, that Biden is not as “electable” as his campaign has suggested — and that the party would be better served by a candidate, like Booker, with a stronger record on issues of race and justice. Booker’s argument comes as Biden continues to lead with African American voters.

“It is easy to call Donald Trump a racist now — you get no great badge of courage for that,” Booker said during remarks at a National Urban League event Thursday in Indianapolis. “The question is, what were you doing to address structural inequality and institutional racism throughout your life?”

One source close to Biden’s campaign said Booker seems to be taking a page from the “Kamala playbook” — hoping to inject life into his own campaign by drawing blood from the current frontrunner.

But Booker’s campaign points out that he has only challenged Biden selectively, on Booker’s own signature issues — which, as one of two African American candidates in the race, Booker is also uniquely positioned to speak to. It’s no dramatic strategic shift, they say, but a natural evolution as the campaign progresses.

“We’re not going down the Republican road of attacking each other on hand sizes,” one Booker campaign aide said. “We’re supposed to have this debate on policy. …You can disagree on issues and still run a positive campaign.”

For the candidate whom Kellyanne Conway likened to “a Hallmark card,” making this transition to a more aggressive phase of campaigning could be awkward. But Booker has consistently stressed his own political duality. Yes, he speaks often about love, unity, etc. Yet he came up as a young politician in hardscrabble Newark, fighting entrenched machines for a foothold on power.

In one scene, Booker wrestles with how to respond to a negative attack by James, saying: “I’m not going to lose this race because we’re afraid to punch Sharpe in the nose. I just think that there’s a way to do it with dignity.” Booker would go on to lose that race to James.

Drawing contrasts with those rivals, while hewing to his own political compass, doesn’t come naturally to Booker.

In April, a Booker campaign email to supporters implicitly criticized former Rep. John Delaney for self-funding his campaign, saying it was “something Cory just can’t and would never do.” Aside from the head-scratching target — why John Delaney? — the jab seemed at odds with Booker’s relentlessly positive message. The candidate himself seemed to agree: Afterward, Booker insisted he didn’t know anything about the email; and, moreover, he wouldn’t approve of such a hit against a rival.

“We are not taking swipes at other candidates,” Booker added. “The reality is, we need to have a Democratic Party that shows how you run a campaign by respecting people you’re running against, and so I’m going to continue to conduct myself in that manner.”

But that has not yet translated to committed support for Booker. Now, the pressure is building for Booker to begin to convert them — a process that could begin next week, when he stands adjacent to Biden on the debate stage.

Booker “is everybody’s favorite cheerleader, but he’s not seen as the quarterback,” Murray said. “He does need to do something to change people’s perceptions.”