Washington (CNN) Michael Bloomberg apologized Sunday for the New York Police Department's use of "stop and frisk," a policing tactic the former mayor and potential 2020 candidate has repeatedly defended as helping to lower the murder rate during his time in office while critics have slammed the measure as racist because it overwhelmingly impacts men of color.

The apology came during remarks the former three-term mayor made at a predominately African American mega church in Brooklyn, New York, where he addressed "stop and frisk," a type of aggressive policing that allowed -- some say encouraged -- officers to detain a person on virtually any type of vague suspicion, search that individual without a warrant and arrest the person if any kind of illegal substance or weapon was found.

The policing approach, officially called "Stop, question and frisk," sparked a backlash from activists throughout Bloomberg's tenure as mayor because it disproportionately affected African American and Latino men.

"Now hindsight is 20/20. But as crime continued to come down as we reduced stops and as it continued to come down during the next administration to its credit, I now see that we could and should have acted sooner. And acted faster to cut the stops. I wish we had. And I'm sorry that we didn't," Bloomberg said.

"But I can't change history, however today I want you to know that I realize back then I was wrong and I'm sorry."

The former mayor's reversal comes months after he defended the policing tactic in January as he publicly mulled a 2020 bid at the time. Bloomberg, who has recently filed paperwork to get on the Democratic primary ballots in two states, is now again considering jumping in the race, and his new comments could be viewed by potential voters as an attempt by the former mayor to abandon what is arguably one of the most controversial aspects of his tenure in the run-up to an official campaign announcement.

'A decade late'

Jumaane Williams, the public advocate for the city of New York, slammed Bloomberg for his apology Sunday, saying that it comes "a decade late."

"Forgive many of us for questioning apologies a decade late and on the eve of a presidential run. It is not nearly enough to erase the legacy of the systemic abuses of stop, question, and frisk on the people whose lives were harmed by over-policing, nor the communities criminalized by it," Williams said in a statement.

Williams continued: "Stop and frisk was just one of many tactics pursued by the Bloomberg administration which had a detrimental impact on lower income New Yorkers and communities of more color."

The initiative grew out of the tough policies of Rudy Giuliani when he was mayor of New York.

"Stop and frisk" continued into Bloomberg's administration, peaking at 203,500 stops during the first three months of 2012 , before declining by about 95% by the end of his run as mayor at the end of 2013 -- after the police department issued a memo announcing changes to its tactics.

More than 5 million "Stop and Frisk" stops were made during Bloomberg's 12 years in office, with nearly 686,000 stops in 2011 being the high point during his overall tenure, according to the New York Civil Liberties Union. African American and Latinos accounted for more than 50% of the stops in 70 out of 76 New York precincts and more than 90% in 32 precincts, according to the ALCU's report released in August 2014

"Though they accounted for only 4.7 percent of the city's population, black and Latino males between the ages of 14 and 24 accounted for 41 percent of stops between 2003 and 2013," the ALCU said in the report. "Nearly 90 percent of young black and Latino men stopped were innocent."

Under Bloomberg, however, New York City's incarceration rate declined , according to data from the city.

During Bloomberg's remarks Sunday morning, the three-term mayor told the congregation that "over time I've come to understand something that I've long struggled to admit to myself -- I got something important wrong."

"I didn't understand that back then, the full impacts that (police) stops were having on the Black and Latino communities. I was totally focused on saving lives. But as we know, good intentions aren't good enough," he said.

Asked about the tactic in January by an audience member at the United States Naval Academy's 2019 Leadership Conference, Bloomberg offered a full-throated defense: "We focused on keeping kids from going through the correctional system ... kids who walked around looking like they might have a gun, remove the gun from their pockets and stop it."

He added that "the result of that was, over the years, the murder rate in New York City went from 650 a year to 300 a year when I left."

2020 looms

A 2018 report from the Equal Justice Initiative, a nonprofit that works against mass incarceration, found that murder rates continued to fall after "stop and frisk" was phased out and called into question the pollicy's effectiveness.

During remarks to civil rights leaders at the National Action Network in Washington earlier in January, Bloomberg didn't mention "stop and frisk," instead admitting to those gathered that he couldn't "stand up here and tell you every decision I have made as mayor was perfect."

The Rev. Al Sharpton, who said he spoke on the phone with Bloomberg following Sunday's apology, welcomed the former mayor's remarks but reminded him that "it will take more than one speech for people to forgive and forget a policy that so negatively impacted entire communities."

Sharpton also expressed skepticism about the timing of Bloomberg's apology, saying, "We will have to wait and see whether it was politically motivated."

Earlier this month, Bloomberg's team filed paperwork to get on the Democratic primary ballot in Alabama and Arkansas. His spokesman Howard Wolfson had previously said if Bloomberg decided to launch a 2020 bid he would not run in the first four contests: Iowa, New Hampshire, Nevada and South Carolina. African American Democratic voters play a crucial role in both the primary and general elections in the Palmetto State.

New York City Mayor Bill de Blasio assailed Bloomberg's decision to apologize for "stop and frisk" on the verge of a possible 2020 run, casting the decision in an interview with CNN as politically craven and referring to it as a "death bed conversion."

De Blasio, who dropped out of the 2020 race earlier this year, said that Bloomberg had six years since the end of his tenure to re-think his support for "stop and frisk" but instead was notably dismissive of anyone who said he had been wrong on the policy.

"He had almost six full years to say it was wrong ... we have had plenty of inflection points where he could have said, 'You know what, I was wrong,'" de Blasio said in a phone interview Sunday. "He has never cared to do that. And I think that says something about the veracity of this."