New York City Police Commissioner Bill Bratton to resign

New York Police Commissioner Bill Bratton speaks to reporters at a news conference following an NYPD Swearing-In Ceremony with Mayor Bill de Blasio on January 7, 2015 in New York City.

Spencer Platt, Getty Images

Last Updated Aug 2, 2016 2:56 PM EDT

NEW YORK -- The commissioner of New York City's police force will resign next month, New York City Mayor Bill de Blasio announced Tuesday.

William Bratton confirmed in July that he did not plan to remain as head of the New York Police Department past the end of Mayor Bill de Blasio's first term in 2017, but did not indicate when he intended to leave the post.

James O'Neill, currently the Chief of Department for the force, will be promoted to commissioner following Bratton's departure. O'Neill was promoted to his current position by Bratton in October 2014, and Bratton has long praised his work.

Tuesday, de Blasio said Bratton's contributions to law enforcement across the city and the country are "literally inestimable and extraordinary."

In the 31 months Bratton has been in office, de Blasio said, the city has worked toward "a goal of doing two things that many said could not be done at the same time - driving down crime while repairing some of the rift between the police and the community."

"We have a long way to go, but I don't think any of us could have imagined a more productive 31 months," he said.

De Blasio also heralded O'Neill as someone who would lead a push toward neighborhood policing, or trying to build trust and working relationships between police and communities. Under Bratton, the city already has made plans to shift toward the neighborhood policing strategy. O'Neill has been heavily involved in those efforts, and de Blasio said neighborhood policing would be in place in 51 precincts as of this fall.

De Blasio said O'Neill, who he described as the "architect" of neighborhood policing, is the "perfect person to succeed" Bratton.

O'Neill started his career in the NYPD in the 1980s as a transit patrolman and has risen through the ranks at the department, "serving in nearly every unformed position in the force," later running precincts, narcotics and fugitive apprehension before his 2014 appointment to Chief of Department, according to the mayor's office.

O'Neill "is ready to take this department where it's never been before in terms of a truly deep and consistent bond between police and community," de Blasio said.

"Police Commissioner Bratton has been a mentor to me both professionally and personally," O'Neill said in a statement. "He has given us a fast ship - as he so often says - and left this department in impressive shape."

Bratton said he had received several offers and had accepted one of them, but wouldn't elaborate. He said he would remain in New York City. The Wall Street Journal reports Bratton will take a job with consulting firm Teneo, where he will run a new risk division.

"It's a bittersweet moment," Bratton said. "I wish I had many more years to stay and deal with the issues facing this city, facing this department, facing this country. But I don't."

He described policing as "unfinished business" and said the city has years of work ahead.

"Better to leave at this juncture with a team that's energetic, that's creative, that wants to engage," he said.

The announcement comes the day after a group of protesters associated with the Black Lives Matter movement rallied outside City Hall demanding Bratton be fired from the NYPD. Bratton said Monday that he had "no concern about being fired."

It is the second time that Bratton, who took office in 2014, has served in the role for fewer than three years. He was previously New York City police commissioner from Jan. 1, 1994 through April 15, 1996, under then-Mayor Rudolph Giuliani.

With the city's crime rate mostly holding at historic lows, Bratton has been credited with helping bolster the de Blasio administration's public safety record. Last week, the mayor downplayed news of Bratton's plans, calling them "very premature."

Bratton's resume is unmatched in local law enforcement. A career that began as a patrolman in Boston in 1970 has seen stints as the head of departments in Boston, Los Angeles and New York.

Though de Blasio was elected as a sharp critic of the police tactic known as stop-and-frisk, he picked Bratton as a sign that he would balance reforming the police department while trying to further drive down crime. On Bratton's watch, the NYPD has drastically scaled back stop-and-frisk but stepped up enforcement of so-called "quality of life" offenses - an approach critics say still unfairly targets minorities and came into play in the police chokehold death of Eric Garner during his arrest for allegedly selling loose cigarettes on a Staten Island block.

Garner, who was black, was unarmed; Officer Daniel Pantaleo, who put his arm around Garner's neck, is white.

Adding to a national wave of concern about police treatment of minorities, Garner's 2014 death and a grand jury's decision not to indict Pantaleo sparked protests and tension between the mayor and rank-and-file officers who felt he took protesters' side.

Then Officers Wenjian Liu and Rafael Ramos were ambushed and shot dead by a gunman who had announced online he planned to kill police in retaliation for Garner's death. In an extraordinary display of scorn, officers turned their back on the mayor at a hospital on the night of the December 2014 killings and again at the officers' funerals.

Bratton found himself in the middle, calling the officers' gesture inappropriate but at the same time noting that it reflected officers' feelings about "many issues."

The tensions between the mayor and police eventually eased, but officers have been under scrutiny this summer as concern about police-minority relations has welled anew here and elsewhere.

On Monday, Bronx state Assemblyman Michael Blake, who is black, filed an excessive-force complaint against the NYPD, saying an officer handled him roughly as Blake tried to defuse an argument between officers and residents. The department said that the officer perceived a possible threat to a sergeant when Blake placed a hand on his shoulder and that the officer had apologized.

Bratton's resignation comes a day after Quinnipiac University released a poll finding New Yorkers are sharply divided on how the city is handling crime, but more than half of respondents said they approved of how Bratton was handling his job.

As tensions between the police and minorities have grown, the mayor, were he to be re-elected next year, will likely be under pressure by his liberal allies to select a more progressive candidate, and likely a commissioner of color.

O'Neill, like Bratton and de Blasio, is white.