The Trump administration plans to tap a top White House lawyer as the next head of the Drug Enforcement Administration, according to people familiar with the decision, which could be announced in coming days.

Uttam Dhillon, who as a deputy White House counsel has played a key role in internal discussions surrounding the firing of FBI director James B. Comey and the special counsel’s probe into Russian interference in the 2016 election, will start at the DEA next week, according to a plan for the staffing move.

His predecessor, Robert W. Patterson, announced this month he was leaving the agency after a 30-year DEA career. In making the announcement he was retiring, Patterson cited the challenges of leading the agency as an acting administrator.

Dhillon has worked at the Justice Department before and was once a federal prosecutor in Los Angeles. He also has worked as a lawyer for the House Financial Services Committee and the House Homeland Security Committee, and served as director of the Office for Counternarcotics Enforcement in the Department of Homeland Security.

Nicola T. Hanna, the U.S. attorney for Los Angeles, worked with Dhillon when they were both federal narcotics prosecutors there in the 1990s.

"He's very smart, he's very familiar with the issues, and he's an exceptionally hard worker," said Hanna, who said that as prosecutors handling major narcotics investigations, most of their cases centered on Colombian and Mexican drug cartels.  

Dhillon probably will be moved into a Justice Department job so that he can be named DEA administrator without a presidential nomination and Senate confirmation. The department is facing a quick deadline to fill the post, as Patterson’s departure is imminent.

A senior administration official said that when Patterson leaves his post, Preston L. Grubbs, the current principal deputy administrator, will lead the agency on a temporary basis, with a formal announcement on Dhillon coming later. Dhillon also is expected to serve in an acting capacity, but by being a Justice Department employee before he goes to the DEA, he will avoid the time limits placed on other acting heads of agencies.

The head of the DEA is a particularly important post in the Trump administration. The agency is playing a key role in Attorney General Jeff Sessions’s crackdown on the opioid epidemic.

Its work is also likely to be affected by Sessions’s directive this year making it easier for U.S. prosecutors to enforce federal marijuana laws in states that had legalized the substance. That directive has generated significant controversy and confusion, and it has been criticized by jurisdictions that have approved pot use and entrepreneurs in the industry.

Dillon did not return messages seeking comment. Mary Brandenberger, a DEA spokeswoman, said she did not yet have information on who would be selected to lead the agency after Patterson’s departure.

This post has been updated.