A Tale of Two Cities—that was the message that swept Bill de Blasio into City Hall. A promise to break down the barriers between the haves and the have-nots, to close the gap of income inequality and, most of all, end years of racial discrimination at the hands of the NYPD over a policing tactic known as Stop-and-Frisk.

"My point is I am the only candidate that would do the three things that would actually end the Stop-and-Frisk era. That is a fact and I stand by it," de Blasio said during a debate in 2013.

It was that message, brought to life by Dante, his 15 year old black son seen in an ad that catapulted de Blasio to become New York City’s 109th mayor.

Now, Stop-and-Frisk is once again in the headlines after de Blasio's predecessor, Michael Bloomberg, issued an apology for the practice over the weekend. It was a stunning reversal, from a man not known for admitting errors. In fact, Bloomberg defended the policy just this past January.

The timing of Bloomberg's apology coincides with a possible White House bid. And now, Bill de Blasio — who saw his own White House bid fail this year — is once again on the attack.

The mayor took to social media following the apology, slamming his predecessor, accusing him of political expediency. Then it was on to national television.

"I just have to say, people aren’t stupid. Like, they can figure out whether someone is honestly addressing an issue or whether they’re acting out of convenience," de Blasio said Sunday during an appearance on CNN.

But de Blasio has his own police problems to worry about now that he's occupied City Hall for six years.

He's faced criticism that despite successfully running on a platform to undo Bloomberg's policing tactics, some believe the NYPD — at de Blasio's direction — is still using race-based tactics, including broken-windows policing and his support for adding more officers to patrol the city's subways. Still, he believes the damage of stop-and-frisk is greater.  

"I'm in the school that says millions of people were hurt by this policy, literally millions of people. So many families. 700,000 people were stopped in 2011. So some might forgive, but very few are going to forget," de Blasio said Monday during his weekly appearance on NY1's Inside City Hall.

Over the years, de Blasio has walked a tight rope in his relationship with the NYPD. He's presided over a department responsible for the lowest crime rates in a generation. He's been hesitant to criticize the department in times of controversy and he would not say whether he believed Officer Daniel Pantaleo, the officer who placed Eric Garner in a fatal chokehold, should be fired from the force.

De Blasio has also been criticized by former allies on the left, most recently over the appointment of yet another white man to lead the NYPD as commissioner.

Much like in the race for mayor six years ago, de Blasio could once again find himself at the center of debate should he choose to push back against a Bloomberg nomination. It’s national attention that de Blasio could crave after ending his own run for president in September.