NEW YORK (CBSNewYork/AP) — NYPD Chief of Department Philip Banks III is resigning.

Banks posted on Twitter that he decided to step down because of professional reasons.

READ MORE: Meisha Porter Stepping Down As New York City Schools Chancellor

Just days ago, it was announced that Banks, 51, was being promoted to First Deputy Commissioner Monday.

That person is second in command at the nation’s largest police department, but it’s a civilian post and Banks would have become less involved in the department’s daily operations.

“I had every confidence that he could fulfill it as well as the expanded responsibilities that we were going to put into that office, which was going to focus very heavily on our personnel development training initiatives at the academy and also the significant rebuilding of relationships with the minority communities,” Commissioner Bill Bratton said Friday.

CBS2 Political Reporter Marcia Kramer reported Bratton was blindsided by Banks’ announcement.

“This is an unfortunate setback, but it’s a momentary setback,” he said.

Sources told CBS2 that Banks, a 28-year NYPD veteran, had been seeking – and was originally promised – more power for the First Deputy Commissioner post. In the past, the position has been largely ceremonial.

Sources told Banks was promised oversight over NYPD operations, but quit when Bratton had a change of heart.

But Bratton denied a blow up with Banks and batted away an assertion that the First Deputy Commissioner has nothing to do, WCBS 880’s Rich Lamb reported.

“That is the most significant position in the New York City Police Department outside of the position of commissioner,” Bratton said.

READ MORE: COVID-19 Update: Researchers Say Omicron Variant Could Quickly Outpace Delta Variant In Cases Across The U.S.

Bratton told reporters he thinks the world of Banks and that it’s with great regret that he accepts his resignation, 1010 WINS’ Carol D’Auria reported.

Mayor Bill de Blasio said he was disappointed to hear of Banks’ decision to step down.

“He has served New York City admirably during his nearly 30 years on the force, and we were enthusiastic about the leadership and energy he would have brought to the position of First Deputy Commissioner,” de Blasio said in a statement.

Banks, a 28-year veteran of the force, was officially installed as the NYPD’s highest-ranking uniformed officer in March 2013.

He is the second African-American to hold the top uniform position. Banks has been with the department since 1986. He was previously the head of community affairs.

The departure left the department with a diversity issue in its upper echelons, and pressure from the Rev. Al Sharpton to fill the post with what he called someone “sensitive to police-community relations.”

The Rev. Kirsten John Foy, a leader in the National Action Network, said Sharpton was in Missouri Friday. But he said Sharpton spoke to Mayor de Blasio about filling the post.

“We care about diversity. We care about the reforms we have been fighting for for years, and so we are concerned. We’re concerned about what it looks like at the top; who is going to be replacing Chief Banks,” Foy said.

Bratton said he would like to move quickly to fill the position, and it was clear the mayor would like to see it go to an African-American. So far, two names under consideration are Gerald Nelson – Chief of Patrol for Brooklyn Borough North – and Kim Royster, who runs the public affairs office for Bratton.

Check Out These Other Stories From CBSNewYork.com:

[display-posts category=”news” wrapper=”ul” posts_per_page=”4″]

MORE NEWS: Supreme Court Signals Support For Upholding Mississippi Abortion Ban

(TM and © Copyright 2014 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2014 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)