Jim Carroll, a deputy to White House chief of staff John Kelly John Francis KellyMORE, will leave his post to become the administration's drug czar, White House press secretary Sarah Huckabee Sanders announced Friday.

President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE plans to nominate Carroll to lead the Office of National Drug Control Policy (ONDCP) where Sanders said the administration has "full confidence" that he will "lead ONDCP to make significant strides in combatting the opioids crisis, reducing drug use, and coordinating U.S. drug policy."

Trump's first nominee for that post, Rep. Tom Marino (R-Penn.), withdrew last year after it was revealed that he had helped guide legislation that critics argue makes it harder for the Drug Enforcement Administration to freeze suspicious shipments of opioids.

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The departure of Carroll, who has served as a senior administration lawyer, comes as the White House scrambles to contain the fallout over its handling of domestic abuse allegations against former staff secretary Rob Porter.

Porter resigned on Wednesday after news reports surfaced detailing allegations that he physically and emotionally abused two ex-wives. Photos also circulated showing one of his former wives with a black eye that Porter allegedly gave her.

Senior White House officials, including Kelly, reportedly knew about the allegations against Porter for months, including that the aide had not obtained a full security clearance because of the accusations.

Prior to becoming joining Kelly's office, Carroll worked in the White House counsel's office. In that role, he oversaw security clearance procedures, one source told The Hill.

Two sources told CNN that Carroll's departure was in the works before Porter resigned this week.

Kelly picked Carroll to join his office after his former deputy, Kirstjen Nielsen Kirstjen Michele NielsenDHS IG won't investigate after watchdog said Wolf, Cuccinelli appointments violated law Appeals court sides with Trump over drawdown of immigrant protections Democrats smell blood with new DHS whistleblower complaint MORE, was picked by Trump to serve as Homeland Security secretary, though Carroll was never formally named deputy chief of staff.

A Politico report published Thursday indicated that while Carroll had taken on some of Nielsen's previous responsibilities, Kelly had become disappointed with the quality of his work.

Carroll is heading to the anti-drug office as the Trump administration is poised to release its budget Monday. The budget is expected to move two major grants out of ONDCP and into other departments, resulting in a 95 percent reduction to the office.

However, it's unlikely that Congress will go along with the budget. The proposal, which was first revealed last month, has faced pushback from a bipartisan group of senators, including Sen. John Cornyn John CornynBipartisan praise pours in after Ginsburg's death Chamber of Commerce endorses McSally for reelection Airline job cuts loom in battleground states MORE (Texas), the No. 2 Senate Republican, and Judiciary Committee Chairman Chuck Grassley Charles (Chuck) Ernest GrassleySenate Republicans face tough decision on replacing Ginsburg What Senate Republicans have said about election-year Supreme Court vacancies Biden says Ginsburg successor should be picked by candidate who wins on Nov. 3 MORE (R-Iowa.). They argue it would hurt the federal government's efforts to curb the opioid epidemic.

Advocacy organizations have also decried the move, saying it would jeopardize the grant programs aimed at reducing substance abuse in youth and coordinating efforts to curb drug trafficking.

Created in 1988, ONDCP is charged with advising the president on drug-related issues, coordinating the federal government's efforts to reduce drug use and crafting an annual national drug control strategy.

The office has been operating without a Senate-confirmed leader. Kellyanne Conway Kellyanne Elizabeth ConwayGeorge and Kellyanne Conway honor Ginsburg Trump carries on with rally, unaware of Ginsburg's death George Conway hits Trump on 9/11 anniversary: 'The greatest threat to the safety and security of Americans' MORE, a counselor to the president, has been taking the lead on the White House's effort to curb the nation's epidemic of opioid overdose deaths, rates that rose nearly 28 percent from 2015 to 2016, according to Centers for Disease Control and Prevention data.

– Reid Wilson, Jonathan Easley and Rachel Roubein contributed

Updated at 6:47 p.m.