President Donald Trump and Labor Secretary Alexander Acosta speak to the media early July 12, 2019 at the White House in Washington, DC. Brendan Smialowski | AFP | Getty Images

Following Alex Acosta's resignation as secretary of Labor, President Donald Trump has over a dozen high-level acting officials leading agencies in his administration. All of these positions require Senate confirmation, except for White House chief of staff. Acting officials can serve for no more than 210 days under the Federal Vacancies Reform Act of 1998. Trump has expressed a preference for acting officials. "It's easier to make moves when they're acting," Trump said on CBS' Face The Nation in February. " I like 'acting' because I can move so quickly. It gives me more flexibility." Within Trump's cabinet, the Pentagon's Mark Esper, Homeland Security's Kevin McAleenan, and now, Labor's Patrick Pizzella serve in an acting capacity. So do Trump's U.N. Ambassador, and Small Business administrator. The White House did not respond to a request for comment.

Department of Defense

Esper took over from former acting Defense Secretary Patrick Shanahan June 18 after Shanahan resigned amid a domestic abuse scandal. Esper had been the secretary of the Army since 2017, before which he was an executive at defense contractor Raytheon. Esper's deputy Defense secretary, longtime federal employee David Norquist, is also serving in an acting capacity. Trump has announced he intends to nominate both men for their positions full-time, but has yet to submit them for Senate confirmation. Trump's original Defense secretary, James Mattis, quit at the end of 2018 over disagreements with Trump's foreign policy. Mattis told Trump he had "a right to a Secretary of Defense whose view are better aligned with yours" in a letter at the time. His resignation came on the heels of Trump's decision to pull U.S. troops out of Syria.

Department of Homeland Security

McAleenan, previously the CBP chief, stepped up to DHS secretary when Trump fired former secretary Kirstjen Nielsen in April. McAleenan is a career federal law enforcement official who previously served in a variety of capacities at CBP and the U.S. Customs Service. His position at CBP was being filled by an acting official, John Sanders, who stepped down July 5, according to CNN. The position is now being filled by another acting official, former acting ICE director Mark Morgan, according to The Wall Street Journal. Trump has not yet announced a nominee for the new DHS head. He announced Morgan as his pick for ICE director, but has not yet officially nominated Morgan.

Department of Labor

Trump announced this morning that Deputy Secretary of Labor Pizzella would fill Acosta's position at the Department of Labor. He has been in federal service since 2013 as a member of the Federal Labor Relations Authority and then its acting chair. The Senate confirmed him as deputy Labor secretary in 2018. @realDonaldTrump: ....Alex was a great Secretary of Labor and his service is truly appreciated. He will be replaced on an acting basis by Pat Pizzella, the current Deputy Secretary. Prior to his government service, Pizzella ran a consulting firm and worked with disgraced lobbyist Jack Abramoff to hamper worker protections in the Northern Mariana Islands.

White House Chief of Staff

Acting chief of staff Mick Mulvaney is a former South Carolina congressman and also still serves as the director of the Office of Management and Budget. For a time, he led the OMB while also serving as the acting head of the Consumer Financial Protection Bureau. Mulvaney is Trump's third chief of staff, following John Kelly and Reince Priebus. Despite not needing Senate confirmation, Mulvaney has kept the "acting" title since assuming the position in mid-December 2018. At the time, a White House official told NBC that Mulvaney's term as acting chief of staff is "indefinite." Two sources told NBC that Mulvaney asked for the "acting" title. One person said he wanted to ensure a safe exit from the position.

U.N. Ambassador

Acting U.S. Ambassador to the United Nations Jonathan Cohen is a career diplomat. Trump has nominated current Ambassador to Canada Kelly Knight Craft to take the role on a permanent basis. After former ambassador Nikki Haley left the job in December 2018, the administration decided the U.N. ambassador would no longer be a Cabinet-level post, according to NBC News. The president has the discretion to include or omit the position from the Cabinet. Former Fox News host and then-State Department spokeswoman Heather Nauert was initially chosen for the position when Haley resigned, but later dropped out of consideration for family reasons.

Small Business Administration

Acting Small Business Administrator Chris Pilkerton was the SBA's general counsel, and previously spent time in the private sector at J.P. Morgan Chase and NASDAQ, and the public sector in the Securities and Exchange Commission and the Manhattan District Attorney's office. Trump announced in April that U.S. Treasurer Jovita Carranza was his choice for the next permanent SBA chief, but he has yet to submit her nomination to the Senate. The SBA administrator is a Cabinet-level position.

Other senate-confirmed positions