WASHINGTON – Acting Drug Enforcement Administration chief Chuck Rosenberg, appointed two years ago to bring stability to an agency riven by controversy, announced late Tuesday that he was stepping down, effective Oct. 1.

Rosenberg, a long-time Justice Department official who also served as a two-time U.S. attorney and a chief of staff to former FBI Director James Comey, was appointed slightly more than two years following a series of scandals that forced the ouster of embattled administrator Michele Leonhart.

"Almost two and half years ago, I wrote to express how grateful I was to join the DEA...to see up close your amazing work," Rosenberg wrote in a message to staffers. "I was proud to support your unique and vital mission and to tout your accomplishments everywhere I went. Now, during my last week, I write to thank you for your courage, integrity and devotion."

A holdover from the Obama administration, Rosenberg's departure was not unexpected. Rosenberg worked closely with Comey, the FBI director Trump abruptly fired in May. Rosenberg also once served as a counselor to former FBI Director Robert Mueller, who is now the special counsel directing the investigation into Russia's intervention in the 2016 election.

As the Trump administration ramps up its response to the opioid crisis and formulates a harder line policy on marijuana, it has been considering a slate of other potential nominees to fill the top DEA slot, including New Jersey State Police Superintendent Rick Fuentes.

Fuentes has discussed the job with top Justice officials, according to two people familiar with the matter who were not authorized to speak publicly.

A career New Jersey law enforcement official, Fuentes was appointed to lead the state police in 2003 and is the state's longest serving superintendent.

His candidacy also is supported by the Fraternal Order of Police, the nation's largest police union.

"Col. Fuentes is the consummate cop's cop," FOP President Chuck Canterbury wrote in a July 7 letter to President Trump, urging the superintendent's consideration. "He has earned the respect of his officers and local law enforcement officers throughout the state, as well as his federal counterparts."

Fuentes declined to comment.

Before Rosenberg's appointment by then-Attorney General Loretta Lynch, the DEA had been reeling from a series of scandals under Leonhart, who retired in wake of an internal Justice investigation found that agents participated in sex parties with prostitutes supplied by drug cartels in Colombia.